Tony Pearson is a Master Inventor and Senior IT Architect for the IBM Storage product line at the
IBM Systems Client Experience Center in Tucson Arizona, and featured contributor
to IBM's developerWorks. In 2016, Tony celebrates his 30th year anniversary with IBM Storage. He is
author of the Inside System Storage series of books. This blog is for the open exchange of ideas relating to storage and storage networking hardware, software and services.
(Short URL for this blog: ibm.co/Pearson )
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The technology industry is full of trade-offs. Take for example solar cells that convert sunlight to electricity. Every hour, more energy hits the Earth in the form of sunlight than the entire planet consumes in an entire year. The general trade-off is between energy conversion efficiency versus abundance of materials:
Get 9-11 percent efficiency using rare materials like indium (In), gallium (Ga) or cadmium (Cd).
Get only 6.7 percent efficiency using abundant materials like copper (Cu), tin (Sn), zinc (Zn), sulfur (S), and selenium (Se)
A second trade-off is exemplified by EMC's recent GeoProtect announcement. This appears similar to the geographic dispersal method introduced by a company called [CleverSafe]. The trade-off is between the amount of space to store one or more copies of data and the protection of data in the event of disaster. Here's an excerpt from fellow blogger Chuck Hollis (EMC) titled ["Cloud Storage Evolves"]:
"Imagine a average-sized Atmos network of 9 nodes, all in different time zones around the world. And imagine that we were using, say, a 6+3 protection scheme.
The implication is clear: any 3 nodes could be completely lost: failed, destroyed, seized by the government, etc.
-- and the information could be completely recovered from the surviving nodes."
For organizations worried about their information falling into the wrong hands (whether criminal or government sponsored!), any subset of the nodes would yield nothing of value -- not only would the information be presumably encrypted, but only a few slices of a far bigger picture would be lost.
Seized by the government?falling into the wrong hands? Is EMC positioning ATMOS as "Storage for Terrorists"? I can certainly appreciate the value of being able to protect 6PB of data with only 9PB of storage capacity, instead of keeping two copies of 6PB each, the trade-off means that you will be accessing the majority of your data across your intranet, which could impact performance. But, if you are in an illicit or illegal business that could have a third of your facilities "seized by the government", then perhaps you shouldn't house your data centers there in the first place. Having two copies of 6PB each, in two "friendly nations", might make more sense.
(In reality, companies often keep way more than just two copies of data. It is not unheard of for companies to keep three to five copies scattered across two or three locations. Facebook keeps SIX copies of photographs you upload to their website.)
ChuckH argues that the governments that seize the three nodes won't have a complete copy of the data. However, merely having pieces of data is enough for governments to capture terrorists. Even if the striping is done at the smallest 512-byte block level, those 512 bytes of data might contain names, phone numbers, email addresses, credit cards or social security numbers. Hackers and computer forensics professionals take advantage of this.
You might ask yourself, "Why not just encrypt the data instead?" That brings me to the third trade-off, protection versus application performance. Over the past 30 years, companies had a choice, they could encrypt and decrypt the data as needed, using server CPU cycles, but this would slow down application processing. Every time you wanted to read or update a database record, more cycles would be consumed. This forced companies to be very selective on what data they encrypted, which columns or fields within a database, which email attachments, and other documents or spreadsheets.
An initial attempt to address this was to introduce an outboard appliance between the server and the storage device. For example, the server would write to the appliance with data in the clear, the appliance would encrypt the data, and pass it along to the tape drive. When retrieving data, the appliance would read the encrypted data from tape, decrypt it, and pass the data in the clear back to the server. However, this had the unintended consequences of using 2x to 3x more tape cartridges. Why? Because the encrypted data does not compress well, so tape drives with built-in compression capabilities would not be able to shrink down the data onto fewer tapes.
(I covered the importance of compressing data before encryption in my previous blog post
[Sock Sock Shoe Shoe].)
Like the trade-off between energy efficiency and abundant materials, IBM eliminated the trade-off by offering compression and encryption on the tape drive itself. This is standard 256-bit AES encryption implemented on a chip, able to process the data as it arrives at near line speed. So now, instead of having to choose between protecting your data or running your applications with acceptable performance, you can now do both, encrypt all of your data without having to be selective. This approach has been extended over to disk drives, so that disk systems like the IBM System Storage DS8000 and DS5000 can support full-disk-encryption [FDE] drives.
Last week, I presented IBM's strategic initiative, the IBM Information Infrastructure, which is part of IBM's New Enterprise Data Center vision. This week, I will try to get around to talking about some of theproducts that support those solutions.
I was going to set the record straight on a variety of misunderstandings, rumors or speculations, but I think most have been taken care of already. IBM blogger BarryW covered the fact that SVC now supports XIV storage systems, in his post[SVC and XIV],and addressed some of the FUD already. Here was my list:
Now that IBM has an IBM-branded model of XIV, IBM will discontinue (insert another product here)
I had seen speculation that XIV meant the demise of the N series, the DS8000 or IBM's partnership with LSI.However, the launch reminded people that IBM announced a new release of DS8000 features, new models of N series N6000,and the new DS5000 disk, so that squashes those rumors.
IBM XIV is a (insert tier level here) product
While there seems to be no industry-standard or agreement for what a tier-1, tier-2 or tier-3 disk system is, there seemed to be a lot of argument over what pigeon-hole category to put IBM XIV in. No question many people want tier-1 performance and functionality at tier-2 prices, and perhaps IBM XIV is a good step at giving them this. In some circles, tier-1 means support for System z mainframes. The XIV does not have traditional z/OS CKD volume support, but Linux on System z partitions or guests can attach to XIV via SAN Volume Controller (SVC), or through NFS protocol as part of the Scale-Out File Services (SoFS) implementation.
Whenever any radicalgame-changing technology comes along, competitors with last century's products and architectures want to frame the discussion that it is just yet another storage system. IBM plans to update its Disk Magic and otherplanning/modeling tools to help people determine which workloads would be a good fit with XIV.
IBM XIV lacks (insert missing feature here) in the current release
I am glad to see that the accusations that XIV had unprotected, unmirrored cache were retracted. XIV mirrors all writes in the cache of two separate modules, with ECC protection. XIV allows concurrent code loadfor bug fixes to the software. XIV offers many of the features that people enjoy in other disksystems, such as thin provisioning, writeable snapshots, remote disk mirroring, and so on.IBM XIV can be part of a bigger solution, either through SVC, SoFS or GMAS that provide thebusiness value customers are looking for.
IBM XIV uses (insert block mirroring here) and is not as efficient for capacity utilization
It is interesting that this came from a competitor that still recommends RAID-1 or RAID-10 for itsCLARiiON and DMX products.On the IBM XIV, each 1MB chunk is written on two different disks in different modules. When disks wereexpensive, how much usable space for a given set of HDD was worthy of argument. Today, we sell you abig black box, with 79TB usable, for (insert dollar figure here). For those who feel 79TB istoo big to swallow all at once, IBM offers "capacity on demand" pricing, where you can pay initially for as littleas 22TB, but get all the performance, usability, functionality and advanced availability of the full box.
IBM XIV consumes (insert number of Watts here) of energy
For every disk system, a portion of the energy is consumed by the number of hard disk drives (HDD) andthe remainder to UPS, power conversion, processors and cache memory consumption. Again, the XIV is a bigblack box, and you can compare the 8.4 KW of this high-performance, low-cost storage one-frame system with thewattage consumed by competitive two-frame (sometimes called two-bay) systems, if you are willing to take some trade-offs. To getcomparable performance and hot-spot avoidance, competitors may need to over-provision or use faster, energy-consuming FC drives, and offer additional software to monitor and re-balance workloads across RAID ranks.To get comparable availability, competitors may need to drop from RAID-5 down to either RAID-1 or RAID-6.To get comparable usability, competitors may need more storage infrastructure management software to hide theinherent complexity of their multi-RAID design.
Of course, if energy consumption is a major concern for you, XIV can be part of IBM's many blended disk-and-tapesolutions. When it comes to being green, you can't get any greener storage than tape! Blended disk-and-tapesolutions help get the best of both worlds.
Well, I am glad I could help set the record straight. Let me know what other products people you would like me to focus on next.
It's official! My "blook" Inside System Storage - Volume I is now available.
This blog-based book, or “blook”, comprises the first twelve months of posts from this Inside System Storage blog,165 posts in all, from September 1, 2006 to August 31, 2007. Foreword by Jennifer Jones. 404 pages.
IT storage and storage networking concepts
IBM strategy, hardware, software and services
Disk systems, Tape systems, and storage networking
Storage and infrastructure management software
Second Life, Facebook, and other Web 2.0 platforms
IBM’s many alliances, partners and competitors
How IT storage impacts society and industry
You can choose between hardcover (with dust jacket) or paperback versions:
This is not the first time I've been published. I have authored articles for storage industry magazines, written large sections of IBM publications and manuals, submitted presentations and whitepapers to conference proceedings, and even had a short story published with illustrations by the famous cartoon writer[Ted Rall].
But I can say this is my first blook, and as far as I can tell, the first blook from IBM's many bloggers on DeveloperWorks, and the first blook about the IT storage industry.I got the idea when I saw [Lulu Publishing] run a "blook" contest. The Lulu Blooker Prize is the world's first literary prize devoted to "blooks"--books based on blogs or other websites, including webcomics. The [Lulu Blooker Blog] lists past year winners. Lulu is one of the new innovative "print-on-demand" publishers. Rather than printing hundredsor thousands of books in advance, as other publishers require, Lulu doesn't print them until you order them.
I considered cute titles like A Year of Living Dangerously, orAn Engineer in Marketing La-La land, or Around the World in 165 Posts, but settled on a title that matched closely the name of the blog.
In addition to my blog posts, I provide additional insights and behind-the-scenes commentary. If you go to the Luluwebsite above, you can preview an entire chapter in its entirety before purchase. I have added a hefty 56-page Glossary of Acronyms and Terms (GOAT) with over 900 storage-related terms defined, which also doubles as an index back to the post (or posts) that use or further explain each term.
So who might be interested in this blook?
Business Partners and Sales Reps looking to give a nice gift to their best clients and colleagues
Managers looking to reward early-tenure employees and retain the best talent
IT specialists and technicians wanting a marketing perspective of the storage industry
Mentors interested in providing motivation and encouragement to their proteges
Educators looking to provide books for their classroom or library collection
Authors looking to write a blook themselves, to see how to format and structure a finished product
Marketing personnel that want to better understand Web 2.0, Second Life and social networking
Analysts and journalists looking to understand how storage impacts the IT industry, and society overall
College graduates and others interested in a career as a storage administrator
And yes, according to Lulu, if you order soon, you can have it by December 25.
I am still wiping the coffee off my computer screen, inadvertently sprayed when I took a sip while reading HDS' uber-blogger Hu Yoshida's post on storage virtualization and vendor lock-in.
HDS is a major vendor for disk storage virtualization, and Hu Yoshida has been around for a while, so I felt it was fair to disagree with some of the generalizations he made to set the record straight. He's been more careful ever since.
However, his latest post [The Greening of IT: Oxymoron or Journey to a New Reality] mentions an expert panel at SNW that includedMark O’Gara Vice President of Infrastructure Management at Highmark. I was not at the SNW conference last week in Orlando, so I will just give the excerpt from Hu's account of what happened:
"Later I had the opportunity to have lunch with Mark O’Gara. Mark is a West Point graduate so he takes a very disciplined approach to addressing the greening of IT. He emphasized the need for measurements and setting targets. When he started out he did an analysis of power consumption based on vendor specifications and came up with a number of 513 KW for his data center infrastructure....
The physical measurements showed that the biggest consumers of power were in order: Business Intelligence Servers, SAN Storage, Robotic tape Library, and Virtual tape servers....
Another surprise may be that tape libraries are such large consumers of power. Since tape is not spinning most of the time they should consume much less power than spinning disk - right? Apparently not if they are sitting in a robotic tape library with a lot of mechanical moving parts and tape drives that have to accelerate and decelerate at tremendous speeds. A Virtual Tape Library with de-duplication factor of 25:1 and large capacity disks may draw significantly less power than a robotic tape library for a given amount of capacity.
Obviously, I know better than to sip coffee whenever reading Hu's blog. I am down here in South America this week, the coffee is very hot and very delicious, so I am glad I didn't waste any on my laptop screen this time, especially reading that last sentence!
In that report, a 5-year comparison found that a repository based on SATA disk was 23 times more expensive overall, and consumed 290 times more energy, than a tape library based on LTO-4 tape technology. The analysts even considered a disk-based Virtual Tape Library (VTL). Focusing just on backups, at a 20:1 deduplication ratio, the VTL solution was still 5 times per expensive than the tape library. If you use the 25:1 ratio that Hu Yoshida mentions in his post above, that would still be 4 times more than a tape library.
I am not disputing Mark O'Gara's disciplined approach. It is possible that Highmark is using a poorly written backup program, taking full backups every day, to an older non-IBM tape library, in a manner that causes no end of activity to the poor tape robotics inside. But rather than changing over to a VTL, perhaps Mark might be better off investigating the use of IBM Tivoli Storage Manager, using progressive backup techniques, appropriate policies, parameters and settings, to a more energy-efficient IBM tape library.In well tuned backup workloads, the robotics are not very busy. The robot mounts the tape, and then the backup runs for a long time filling up that tape, all the meanwhile the robot is idle waiting for another request.
(Update: My apologies to Mark and his colleagues at Highmark. The above paragraph implied that Mark was using badproducts or configured them incorrectly, and was inappropriate. Mark, my full apology [here])
If you do decide to go with a Virtual Tape Library, for reasons other than energy consumption, doesn't it make sense to buy it from a vendor that understands tape systems, rather than buying it from one that focuses on disk systems? Tape system vendors like IBM, HP or Sun understand tape workloads as well as related backup and archive software, and can provide better guidance and recommendations based on years of experience. Asking advice abouttape systems, including Virtual Tape Libraries, from a disk vendor is like asking for advice on different types of bread from your butcher, or advice about various cuts of meat at the bakery.
The butchers and bakers might give you answers, but it may not be the best advice.
Am I dreaming? On his Storagezilla blog, fellow blogger Mark Twomey (EMC) brags about EMC's standard benchmark results, in his post titled [Love Life. Love CIFS.]. Here is my take:
A Full 180 degree reversal
For the past several years, EMC bloggers have argued, both in comments on this blog, and on their own blogs, that standard benchmarks are useless and should not be used to influence purchase decisions. While we all agree that "your mileage may vary", I find standard benchmarks are useful as part of an overall approach in comparing and selecting which vendors to work with, and which architectures or solution approaches to adopt, and which products or services to deploy. I am glad to see that EMC has finally joined the rest of the planet on this. I find it funny this reversal sounds a lot like their reversal from "Tape is Dead" to "What? We never said tape was dead!"
Impressive CIFS Results
The Standard Performance Evaluation Corporation (SPEC) has developed a series of NFS benchmarks, the latest, [SPECsfs2008] added support for CIFS. So, on the CIFS side, EMC's benchmarks compare favorably against previous CIFS tests from other vendors.
On the NFS side, however, EMC is still behind Avere, BlueArc, Exanet, and IBM/NetApp. For example, EMC's combination of Celerra gateways in front of V-Max disk systems resulted in 110,621 OPS with overall response time of 2.32 milliseconds. By comparison, the IBM N series N7900 (tested by NetApp under their own brand, FAS6080) was able to do 120,011 OPS with 1.95 msec response time.
Even though Sun invented the NFS protocol in the early 1980s, they take an EMC-like approach against standard benchmarks to measure it. Last year, fellow blogger Bryan Cantrill (Sun) gives his [Eulogy for a Benchmark]. I was going to make points about this, but fellow blogger Mike Eisler (NetApp) [already took care of it]. We can all learn from this. Companies that don't believe in standard benchmarks can either reverse course (as EMC has done), or continue their downhill decline until they are acquired by someone else.
(My condolences to those at Sun getting laid off. Those of you who hire on with IBM can get re-united with your former StorageTek buddies! Back then, StorageTek people left Sun in droves, knowing that Sun didn't understand the mainframe tape marketplace that StorageTek focused on. Likewise, many question how well Oracle will understand Sun's hardware business in servers and storage.)
What's in a Protocol?
Both CIFS and NFS have been around for decades, and comparisons can sometimes sound like religious debates. Traditionally, CIFS was used to share files between Windows systems, and NFS for Linux and UNIX platforms. However, Windows can also handle NFS, while Linux and UNIX systems can use CIFS. If you are using a recent level of VMware, you can use either NFS or CIFS as an alternative to Fibre Channel SAN to store your external disk VMDK files.
The Bigger Picture
There is a significant shift going on from traditional database repositories to unstructured file content. Today, as much as [80 percent of data is unstructured]. Shipments this year are expected to grow 60 percent for file-based storage, and only 15 percent for block-based storage. With the focus on private and public clouds, NAS solutions will be the battleground for 2010.
So, I am glad to see EMC starting to cite standard benchmarks. Hopefully, SPC-1 and SPC-2 benchmarks are forthcoming?
As a consultant, I am often asked to help design the architecture for the information infrastructure. A usefulanalogy to gather requirements and preferences is the difference between area rugs and wall-to-wall carpeting. Arearugs are not secured to the floor and cover only a portion of the floor area. Carpets are generally tacked or cemented to the floor, often with an underlay of cushion padding, stretched across the entire floor surface, out to all four walls of each room.
Each has its pros and cons, and often is a matter of preference. Some people like area rugs because they can choosea different style for each room, match the decor and color scheme of furniture, and use these to define each livingspace. Ever since paleolithic man put animal skins on the floor of their cave, people recognize that cold, hard andugly floors could be covered up with something soft and more attractive.Others prefer wall-to-wall carpeting because they want to walk around the house barefoot, have their young children crawl on their hands and knees, and give the entire house a unified look and feel. This is often an inexpensive option when compared against the cost of individual rugs.
The same is true for an information infrastructure. For some, they prefer the "area rug" approach: this style ofstorage for their email, this other type of storage for their databases, and perhaps a third for their unstructuredfile systems. When customers ask what storage would I recommend for their SAP application, or their Microsoft Exchangeemail environment, or their Business Intelligence (BI) software, I recognize they are taking this "area rug" approach.
Like area rugs, having different storage can focus on specific attributes of the workload characteristics. It alsoinsulates against company-wide changes, the dreaded "rip-and-replace" of replacing all of your storage with somethingfrom a different vendor. With "area rug" storage, you can support a dual-vendor or multi-vendor strategy, and upgrade or replace each on its own schedule.
Thanks to open standards and industry-standard benchmarks, changing out one storage solution for another is assimple as rolling up an area rug, and putting another one in its place that is similar in size dimensions.
Others may prefer "wall-to-wall carpeting" approach: one disk system type, one tape library type,one network type, that provides unified management and minimizes the needs for unique skills. Generally, the choice of NAS, SAN or iSCSI infrastrucutre is done company-wide, and might strongly influence the set of products that will support that decision. For example, those with a mix of mainframe and distributed servers looking for SAN-attached storage may look at an [IBM System Storage DS8000] and [TS3500 tape library] that can provide support for FICON and FCP.
Those looking at NAS or iSCSI might consider the IBM System Storage N series products, "unified storage" supporting iSCSI, FCP and NAS protocols. If you want the "wall-to-wall" to stretch across all the sites in your globally integrated enterprise, IBM's scalable NAS product, Scale-Out File Services[SoFS], provides a global name spacein combination with a clustered file system that provides incredible scalability and performance based on field-proven technology used by the majority of the [Top 100 supercomputer] deployments.
IBM can help you design an information infrastructure that fits either approach.
Miles per Gallon measures an effeciency ratio (amount of work done with a fixed amount of energy), not a speed ratio (distance traveled in a unit of time).
Given that IOPs and MB/s are the unit of "work" a storage array does, wouldn't the MPG equivalent for storage be more like IOPs per Watt or MB/s per Watt? Or maybe just simply Megabytes Stored per Watt (a typical "green" measurement)?
You appear to be intentionally avoiding the comparison of I/Os per Second and Megabytes per Second to Miles Per Hour?
May I ask why?
This is a fair question, Barry, so I will try to address it here.
It was not a typo, I did mean MPG (miles per gallon) and not MPH (miles per hour). It is always challenging to find an analogy that everyone can relate to explain concepts in Information Technology that might be harder to grasp. I chose MPG because it was closely related to IOPS and MB/s in four ways:
MPG applies to all instances of a particular make and model. Before Henry Ford and the assembly line, cars were made one at a time, by a small team of craftsmen, and so there could be variety from one instance to another. Today, vehicles and storage systems are mass-produced in a manner that provides consistent quality. You can test one vehicle, and safely assume that all similar instances of the same make and model will have the similar mileage. The same is true for disk systems, test one disk system and you can assume that all others of the same make and model will have similar performance.
MPG has a standardized measurement benchmark that is publicly available. The US Environmental Protection Agency (EPA) is an easy analogy for the Storage Performance Council, providing the results of various offerings to chose from.
MPG has usage-specific benchmarks to reflect real-world conditions.The EPA offers City MPG for the type of driving you do to get to work, and Highway MPG, to reflect the type ofdriving on a cross-country trip. These serve as a direct analogy to SPC having SPC-1 for Online transaction processing (OLTP) and SPC-2 for large file transfers, database queries and video streaming.
MPG can be used for cost/benefit analysis.For example, one could estimate the amount of business value (miles travelled) for the amount of dollar investment (cost to purchase gallons of gasoline, at an assumed gas price). The EPA does this as part of their analysis. This is similar to the way IOPS and MB/s can be divided by the cost of the storage system being tested on SPC benchmark results. The business value of IOPS or MB/s depends on the application, but could relate to the number of transactions processed per hour, the number of music downloads per hour, or number of customer queries handled per hour, all of which can be assigned a specific dollar amount for analysis.
It seemed that if I was going to explain why standardized benchmarks were relevant, I should find an analogy that has similar features to compare to. I thought about MPH, since it is based on time units like IOPS and MB/s, butdecided against it based on an earlier comment you made, Barry, about NASCAR:
Let's imagine that a Dodge Charger wins the overwhelming majority of NASCAR races. Would that prove that a stock Charger is the best car for driving to work, or for a cross-country trip?
Your comparison, Barry, to car-racing brings up three reasons why I felt MPH is a bad metric to use for an analogy:
Increasing MPH, and driving anywhere near the maximum rated MPH for a vehicle, can be reckless and dangerous,risking loss of human life and property damage. Even professional race car drivers will agree there are dangers involved. By contrast, processing I/O requests at maximum speed poses no additional risk to the data, nor possibledamage to any of the IT equipment involved.
While most vehicles have top speeds in excess of 100 miles per hour, most Federal, State and Local speed limits prevent anyone from taking advantage of those maximums. Race-car drivers in NASCAR may be able to take advantage of maximum MPH of a vehicle, the rest of us can't. The government limits speed of vehicles precisely because of the dangers mentioned in the previous bullet. In contrast, processing I/O requests at faster speeds poses no such dangers, so the government poses no limits.
Neither IOPS nor MB/s match MPH exactly.Earlier this week,I related IOPS to "Questions handled per hour" at the local public library, and MB/s to "Spoken words per minute" in those replies. If I tried to find a metric based on unit type to match the "per second" in IOPS and MB/s, then I would need to find a unit that equated to "I/O requests" or "MB transferred" rather than something related to "distance travelled".
In terms of time-based units, the closest I could come up with for IOPS was acceleration rate of zero-to-sixty MPH in a certain number of seconds. Speeding up to 60MPH, then slamming the breaks, and then back up to 60MPH, start-stop, start-stop, and so on, would reflect what IOPS is doing on a requestby request basis, but nobody drives like this (except maybe the taxi cab drivers here in Malaysia!)
Since vehicles are limited to speed limits in normal road conditions, the closest I could come up with for MB/s would be "passenger-miles per hour", such that high-occupancy vehicles like school buses could deliver more passengers than low-occupancy vehicles with only a few passengers.
Neither start-stops nor passenger-miles per hour have standardized benchmarks, so they don't work well for comparisonbetween vehicles.If you or anyone can come up with a metric that will help explain the relevance of standardized benchmarks better than the MPG that I already used, I would be interested in it.
You also mention, Barry, the term "efficiency" but mileage is about "fuel economy".Wikipedia is quick to point out that the fuel efficiency of petroleum engines has improved markedly in recent decades, this does not necessarily translate into fuel economy of cars. The same can be said about the performance of internal bandwidth ofthe backplane between controllers and faster HDD does not necessarily translate to external performance of the disk system as a whole. You correctly point this out in your blog about the DMX-4:
Complementing the 4Gb FC and FICON front-end support added to the DMX-3 at the end of 2006, the new 4Gb back-end allows the DMX-4 to support the latest in 4Gb FC disk drives.
You may have noticed that there weren't any specific performance claims attributed to the new 4Gb FC back-end. This wasn't an oversight, it is in fact intentional. The reality is that when it comes to massive-cache storage architectures, there really isn't that much of a difference between 2Gb/s transfer speeds and 4Gb/s.
Oh, and yes, it's true - the DMX-4 is not the first high-end storage array to ship a 4Gb/s FC back-end. The USP-V, announced way back in May, has that honor (but only if it meets the promised first shipments in July 2007). DMX-4 will be in August '07, so I guess that leaves the DS8000 a distant 3rd.
This also explains why the IBM DS8000, with its clever "Adaptive Replacement Cache" algorithm, has such highSPC-1 benchmarks despite the fact that it still uses 2Gbps drives inside. Given that it doesn't matter between2Gbps and 4Gbps on the back-end, why would it matter which vendor came first, second or third, and why call it a "distant 3rd" for IBM? How soon would IBM need to announce similar back-end support for it to be a "close 3rd" in your mind?
I'll wrap up with you're excellent comment that Watts per GB is a typical "green" metric. I strongly support the whole"green initiative" and I used "Watts per GB" last month to explain about how tape is less energy-consumptive than paper.I see on your blog you have used it yourself here:
The DMX-3 requires less Watts/GB in an apples-to-apples comparison of capacity and ports against both the USP and the DS8000, using the same exact disk drives
It is not clear if "requires less" means "slightly less" or "substantially less" in this context, and have no facts from my own folks within IBM to confirm or deny it. Given that tape is orders of magnitude less energy-consumptive than anything EMC manufacturers today, the point is probably moot.
I find it refreshing, nonetheless, to have agreed-upon "energy consumption" metrics to make such apples-to-apples comparisons between products from different storage vendors. This is exactly what customers want to do with performance as well, without necessarily having to run their own benchmarks or work with specific storage vendors. Of course, Watts/GB consumption varies by workload, so to make such comparisons truly apples-to-apples, you would need to run the same workload against both systems. Why not use the SPC-1 or SPC-2 benchmarks to measure the Watts/GB consumption? That way, EMC can publish the DMX performance numbers at the same time as the energy consumption numbers, and then HDS can follow suit for its USP-V.
I'm on my way back to the USA soon, but wanted to post this now so I can relax on the plane.
EMC Corporation (NYSE:EMC) today announced it has been positioned as a leader in the Forrester Wave™: Enterprise Open Systems Virtual Tape Library (VTL), Q1 2008 by Forrester Research, Inc. (January 31, 2008), an independent market and technology research firm. EMC achieved a position as a leader in the Forrester Wave report on virtual tape libraries based on the largest installed base of the EMC® Disk Library family of systems, its broad ecosystem interoperability. Virtual tape libraries emulate tape drives and work in conjunction with existing backup software applications, enabling fast backup and restoration of data by using high-capacity, low-cost disk drives.
EMC was the first major vendor in the open systems virtual tape library market as it introduced the EMC Disk Library in April 2004 and today is a leading provider of open systems virtual tape solutions, with systems that are designed for businesses and organizations of all sizes.
While the press release implies that "EDL equals VTL", Chuck tries to explain they are in fact very different. Here is an excerpt from his blog post:
Virtual Tape Libraries vs. Disk Libraries
As many of you know, VTLs have been around for a while. They use disk as a cache -- they buffer the incoming backup streams, do some housekeeping and stacking, then turn around and write tape efficiently. When you go to restore, you're usually coming back off of tape, unless the backup image in question is sitting in the disk cache.
Now, there is nothing wrong with the VTL approach, but it was conceived in a time when disks were horribly expensive. It was also pretty clear to many of us that disks were going to be a whole lot cheaper in the near future, and this fundamental assumption wouldn't be valid for much longer.
I kept thinking in terms of disk as a direct target for a backup application. No modifications to the backup application. Native speed of sequential disks for both backup and restore. Tape positioned as a backup to the backup. Use the strengths of the underlying array (e.g. CLARiiON) for performance, availability, management, etc.
We ended up calling the concept a "disk library" to differentiate from the VTLs that had come before it. It was a different value proposition and offering, based on the emergence of lower-cost disk media.
... It's nice to see we're at 1,100+ customers, and still going strong.
For those new to the blogosphere, there is a difference between "Press Releases" as formalcorporate communications versus "Blog Posts" which are informal opinions of the individual blogger, whichmay or may not match exactly the views of their respective employer.As we've learned many times before, one should not treat termslike "first" or "leader" in corporate press releases literally! Let's explore each.
Was EDL the first "open systems" Virtual Tape Library?
This is implied by the Forrester report. Chuck mentions the "VTLs that had came before it" in his blog, and many people are aware that IBM and StorageTek had introduced mainframe-attached VTLs in the 1990s. But what about VTL for "open systems"?
(Hold aside for the moment that IBM System zmainframe is an open system itself, with z/OS certified as a bona fide UNIX operating system by the [the Open Group] standards body. Most analysts and research firms usually refer only to the non-mainframe versions of UNIX and Windows. Alternative definitions for "open systems" can be foundin [Web definitions or Wikipedia]. I will assume Forrester meantnon-mainframe servers.)
IBM announced AIX non-mainframe attachment via SCSI connectivity to the IBM 3494 Virtual Tape Server (VTS) on Feb 16, 1999, with general availability in May 28, 1999. That's nearly FIVE YEARS before the April 2004 introduction of EDL. IBM VTS support for Sun Solaris and Microsoft Windows came shortly thereafter in November 2000, and support for HP-UX a bit later in June 2001. One of my 17 patents is for the software inside the IBM 3494 VTS, so like Chuck, I can takesome pride in the success of a successful product.
(I don't remember if StorageTek, which was subsequently acquired by Sun, had ever supported non-mainframe operating systems with their Virtual Storage Manager[VSM] offering, but if they did, I am sure it was also before EMC.)
Last week, another EMC blogger, BarryB (aka [the Storage Anarchist]),took me to task in comments on my post [IBM now supports 1TB SATA drives]. He felt that IBM should not claim support, given that the software inside the IBM System Storage N series is developed by NetApp. He compared this to the situation of HP and Sun re-badging the HDS USP-V disk system. If someone else wrote the software, BarryB opines, IBM should not claim credit for it. I tried to explain how IBM provides added value and has full-time employees dedicated to N series development and support, butdoubt I have changed his mind.
Why do I bring that up? Because the EMC Disk Library runs OEM software from FalconStor. Basically EMC is assembling a hardware/software solution with components provided from OEM suppliers. Hmmm? Sound familiar? Who is calling the kettle black?
If there is a clear winner here, it is FalconStor itself.Perhaps one of the worst kept industry secrets is that FalconStor software is also used in VTL offerings from Sun, Copan, and IBM, the latter embodied as the [IBM TS7520 Virtualization Engine] offering. If you like the concept of an EDL,but prefer instead one-stop shopping from an "information infrastructure" vendor, IBM can offer the TS7520 along with servers, software and services for a complete end-to-end solution.
Can EMC claim to be "a leader" in Virtual Tape Libraries?
During the measured quarter, IBM shipped its 10 millionth LTO-4 tape drive cartridge to Getty Images, the world's leading creator and distributor of still imagery, footage and multi-media products, as well as a recognized provider of other forms of premium digital content, including music. Getty Images is using the LTO-4 drives as part of a tiered infrastructure of IBM disk and tape solutions that help support the backup needs of their digital imagery;
IBM shipped more than 1,500 Petabytes of tape storage in Q3'07 alone;
During Q3'07, IBM shipped the 10,000th IBM System Storage TS3500 Tape Library. The TS3500 is a highly scalable tape library with support from 1 to 192 tape drives and up to 6,400 cartridge slots for open system, mainframe and virtual tape system attachment.
Let's take a look at the numbers. IBM has sold over 5,400 virtual tape libraries. Sun/STK has sold over 4,000 virtual tape libraries. Both are drastically more than the 1,100 mentioned in Chuck's post. Does IDC recognize EMC in third place? No, EMC chooses instead to declare EDL as disk arrays (probably toprop up their IDC "Disk Tracker" numbers), so they don't even earn an honorable mention under the virtual tape librarycategory. This of course includes the number of mainframe-attached models from IBM and Sun/STK. So, if EMC did call these tape systems instead, they might showup in third place, and as such EMC could claim to be "a leader" in much the same way an athlete can claim to be an "Olympic medalist" winning the bronze for third place. (If you limit thecount to just the FalconStor-based models from IBM, EMC, Sun and Copan, then EMC moves up to first or second, but then press release titles like "EMC a Leader in FalconStor-based non-mainframe Virtual Tape Libraries" can get too confusing.)
Chuck, if you are reading this, I feel you have every right to celebrate your involvement with the EDL. Despite having common software and hardware components, both IBM and EMC can rightfully declare their own unique value-add through their respective VTL offerings. Like the IBM N series, the EMC Disk Library is not diminished by the fact the software was written by someone else. BarryB might disagree.
Continuing my catch-up on past posts, Jon Toigo on his DrunkenData blog, posted a ["bleg"] for information aboutdeduplication. The responses come from the "who's who" of the storage industry, so I will provide IBM'sview. (Jon, as always, you have my permission to post this on your blog!)
Please provide the name of your company and the de-dupe product(s) you sell. Please summarize what you think are the key values and differentiators of your wares.
IBM offers two different forms of deduplication. The first is IBM System Storage N series disk system with Advanced Single Instance Storage (A-SIS), and the second is IBM Diligent ProtecTier software. Larry Freeman from NetApp already explains A-SIS in the [comments on Jon's post], so I will focus on the Diligent offering in this post. The key differentiators for Diligent are:
Data agnostic. Diligent does not require content-awareness, format-awareness nor identification of backup software used to send the data. No special client or agent software is required on servers sending data to an IBM Diligent deployment.
Inline processing. Diligent does not require temporarily storing data on back-end disk to post-process later.
Scalability. Up to 1PB of back-end disk managed with an in-memory dictionary.
Data Integrity. All data is diff-compared for full 100 percent integrity. No data is accidentally discarded based on assumptions about the rarity of hash collisions.
InfoPro has said that de-dupe is the number one technology that companies are seeking today — well ahead of even server or storage virtualization. Is there any appeal beyond squeezing more undifferentiated data into the storage junk drawer?
Diligent is focused on backup workloads, which has the best opportunity for deduplication benefits. The two main benefits are:
Keeping more backup data available online for fast recovery.
Mirroring the backup data to another remote location for added protection. With inline processing, only the deduplicated data is sent to the back-end disk, and this greatly reduces the amount of data sent over the wire to the remote location.
Every vendor seems to have its own secret sauce de-dupe algorithm and implementation. One, Diligent Technologies (just acquired by IBM), claims that their’s is best because it collapses two functions — de-dupe then ingest — into one inline function, achieving great throughput in the process. What should be the gating factors in selecting the right de-dupe technology?
As with any storage offering, the three gating factors are typically:
Will this meet my current business requirements?
Will this meet my future requirements for the next 3-5 years that I plan to use this solution?
What is the Total Cost of Ownership (TCO) for the next 3-5 years?
Assuming you already have backup software operational in your existing environment, it is possible to determine thenecessary ingest rate. How many "Terabytes per Hour" (TB/h) must be received, processed and stored from the backup software during the backup window. IBM intends to document its performance test results of specific software/hardwarecombinations to provide guidance to clients' purchase and planning decisions.
For post-process deployments, such as the IBM N series A-SIS feature, the "ingest rate" during the backup only has to receive and store the data, and the rest of the 24-hour period can be spent doing the post-processing to find duplicates. This might be fine now, but as your data grows, you might find your backup window growing, and that leaves less time for post-processing to catch up. IBM Diligent does the processing inline, so is unaffected by an expansion of the backup window.
IBM Diligent can scale up to 1PB of back-end data, and the ingest rate does not suffer as more data is managed.
As for TCO, post-process solutions must have additional back-end storage to temporarily hold the data until the duplicates can be found. With IBM Diligent's inline methodology, only deduplicated data is stored, so less disk space is required for the same workloads.
Despite the nuances, it seems that all block level de-dupe technology does the same thing: removes bit string patterns and substitutes a stub. Is this technically accurate or does your product do things differently?
IBM Diligent emulates a tape library, so the incoming data appears as files to be written sequentially to tape. A file is a string of bytes. Unlike block-level algorithms that divide files up into fixed chunks, IBM Diligent performs diff-compares of incoming data with existing data, and identifies ranges of bytes that duplicate what already is stored on the back-end disk. The file is then a sequence of "extents" representing either unique data or existing data. The file is represented as a sequence of pointers to these extents. An extent can vary from2KB to 16MB in size.
De-dupe is changing data. To return data to its original state (pre-de-dupe) seems to require access to the original algorithm plus stubs/pointers to bit patterns that have been removed to deflate data. If I am correct in this assumption, please explain how data recovery is accomplished if there is a disaster. Do I need to backup your wares and store them off site, or do I need another copy of your appliance or software at a recovery center?
For IBM Diligent, all of the data needed to reconstitute the data is stored on back-end disks. Assuming that all of your back-end disks are available after the disaster, either the original or mirrored copy, then you only need the IBM Diligent software to make sense of the bytes written to reconstitute the data. If the data was written by backup software, you would also need compatible backup software to recover the original data.
De-dupe changes data. Is there any possibility that this will get me into trouble with the regulators or legal eagles when I respond to a subpoena or discovery request? Does de-dupe conflict with the non-repudiation requirements of certain laws?
I am not a lawyer, and certainly there are aspects of[non-repudiation] that may or may not apply to specific cases.
What I can say is that storage is expected to return back a "bit-perfect" copy of the data that was written. Thereare laws against changing the format. For example, an original document was in Microsoft Word format, but is converted and saved instead as an Adobe PDF file. In many conversions, it would be difficult to recreate the bit-perfect copy. Certainly, it would be difficult to recreate the bit-perfect MS Word format from a PDF file. Laws in France and Germany specifically require that the original bit-perfect format be kept.
Based on that, IBM Diligent is able to return a bit-perfect copy of what was written, same as if it were written to regular disk or tape storage, because all data is diff-compared byte-for-byte with existing data.
In contrast, other solutions based on hash codes have collisions that result in presenting a completely different set of data on retrieval. If the data you are trying to store happens to have the same hash code calculation as completely different data already stored on a solution, then it might just discard the new data as "duplicate". The chance for collisions might be rare, but could be enough to put doubt in the minds of a jury. For this reason, IBM N series A-SIS, that does perform hash code calculations, will do a full byte-for-byte comparison of data to ensure that data is indeed a duplicate of an existing block stored.
Some say that de-dupe obviates the need for encryption. What do you think?
I disagree. I've been to enough [Black Hat] conferences to know that it would be possible to read thedata off the back-end disk, using a variety of forensic tools, and piece together strings of personal information,such as names, social security numbers, or bank account codes.
Currently, IBM provides encryption on real tape (both TS1120 and LTO-4 generation drives), and is working withopen industry standards bodies and disk drive module suppliers to bring similar technology to disk-based storage systems.Until then, clients concerned about encryption should consider OS-based or application-based encryption from thebackup software. IBM Tivoli Storage Manager (TSM), for example, can encrypt the data before sending it to the IBMDiligent offering, but this might reduce the number of duplicates found if different encryption keys are used.
Some say that de-duped data is inappropriate for tape backup, that data should be re-inflated prior to write to tape. Yet, one vendor is planning to enable an “NDMP-like” tape backup around his de-dupe system at the request of his customers. Is this smart?
Re-constituting the data back to the original format on tape allows the original backup software to interpret the tape data directly to recover individual files. For example, IBM TSM software can write its primary backup copies to an IBM Diligent offering onsite, and have a "copy pool" on physical tape stored at a remote location. The physical tapes can be used for recovery without any IBM Diligent software in the event of a disaster. If the IBM Diligent back-end disk images are lost, corrupted, or destroyed, IBM TSM software can point to the "copy pool" and be fully operational. Individual files or servers could be restored from just a few of these tapes.
An NDMP-like tape backup of a deduplicated back-end disk would require that all the tapes are in-tact, available, and fully restored to new back-end disk before the deduplication software could do anything. If a single cartridge fromthis set was unreadable or misplaced, it might impact the access to many TBs of data, or render the entire systemunusable.
In the case of a 1PB of back-end disk for IBM Diligent, you would be having to recover over a thousand tapes back to disk before you could recover any individual data from your backup software. Even with dozens of tape drives in parallel, could take you several days for the complete process.This represents a longer "Recovery Time Objective" (RTO) than most people are willing to accept.
Some vendors are claiming de-dupe is “green” — do you see it as such?
Certainly, "deduplicated disk" is greener than "non-deduplicated" disk, but I have argued in past posts, supportedby Analyst reports, that it is not as green as storing the same data on "non-deduplicated" physical tape.
De-dupe and VTL seem to be joined at the hip in a lot of vendor discussions: Use de-dupe to store a lot of archival data on line in less space for fast retrieval in the event of the accidental loss of files or data sets on primary storage. Are there other applications for de-duplication besides compressing data in a nearline storage repository?
Deduplication can be applied to primary data, as in the case of the IBM System Storage N series A-SIS. As Larrysuggests, MS Exchange and SharePoint could be good use cases that represent the possible savings for squeezing outduplicates. On the mainframe, many master-in/master-out tape applications could also benefit from deduplication.
I do not believe that deduplication products will run efficiently with “update in place” applications, that is high levels of random writes for non-appending updates. OLTP and Database workloads would not benefit from deduplication.
Just suggested by a reader: What do you see as the advantages/disadvantages of software based deduplication vs. hardware (chip-based) deduplication? Will this be a differentiating feature in the future… especially now that Hifn is pushing their Compression/DeDupe card to OEMs?
In general, new technologies are introduced on software first, and then as implementations mature, get hardware-based to improve performance. The same was true for RAID, compression, encryption, etc. The Hifn card does "hash code" calculations that do not benefit the current IBM Diligent implementation. Currently, IBM Diligent performsLZH compression through software, but certainly IBM could provide hardware-based compression with an integrated hardware/software offering in the future. Since IBM Diligent's inline process is so efficient, the bottleneck in performance is often the speed of the back-end disk. IBM Diligent can get improved "ingest rate" using FC instead of SATA disk.
Sorry, Jon, that it took so long to get back to you on this, but since IBM had just acquired Diligent when you posted, it took me a while to investigate and research all the answers.
Continuing my week in Washington DC for the annual [2010 System Storage Technical University], I presented a session on Storage for the Green Data Center, and attended a System x session on Greening the Data Center. Since they were related, I thought I would cover both in this post.
Storage for the Green Data Center
I presented this topic in four general categories:
Drivers and Metrics - I explained the three key drivers for consuming less energy, and the two key metrics: Power Usage Effectiveness (PUE) and Data Center Infrastructure Efficiency (DCiE).
Storage Technologies - I compared the four key storage media types: Solid State Drives (SSD), high-speed (15K RPM) FC and SAS hard disk, slower (7200 RPM) SATA disk, and tape. I had comparison slides that showed how IBM disk was more energy efficient than competition, for example DS8700 consumes less energy than EMC Symmetrix when compared with the exact same number and type of physical drives. Likewise, IBM LTO-5 and TS1130 tape drives consume less energy than comparable HP or Oracle/Sun tape drives.
Integrated Systems - IBM combines multiple storage tiers in a set of integrated systems managed by smart software. For example, the IBM DS8700 offers [Easy Tier] to offer smart data placement and movement across Solid-State drives and spinning disk. I also covered several blended disk-and-tape solutions, such as the Information Archive and SONAS.
Actions and Next Steps - I wrapped up the talk with actions that data center managers can take to help them be more energy efficient, from deploying the IBM Rear Door Heat Exchanger, or improving the management of their data.
Greening of the Data Center
Janet Beaver, IBM Senior Manager of Americas Group facilities for Infrastructure and Facilities, presented on IBM's success in becoming more energy efficient. The price of electricity has gone up 10 percent per year, and in some locations, 30 percent. For every 1 Watt used by IT equipment, there are an additional 27 Watts for power, cooling and other uses to keep the IT equipment comfortable. At IBM, data centers represent only 6 percent of total floor space, but 45 percent of all energy consumption. Janet covered two specific data centers, Boulder and Raleigh.
At Boulder, IBM keeps 48 hours reserve of gasoline (to generate electricity in case of outage from the power company) and 48 hours of chilled water. Many power outages are less than 10 minutes, which can easily be handled by the UPS systems. At least 25 percent of the Computer Room Air Conditioners (CRAC) are also on UPS as well, so that there is some cooling during those minutes, within the ASHRAE guidelines of 72-80 degrees Fahrenheit. Since gasoline gets stale, IBM runs the generators once a month, which serves as a monthly test of the system, and clears out the lines to make room for fresh fuel.
The IBM Boulder data center is the largest in the company: 300,000 square feet (the equivalent of five football fields)! Because of its location in Colorado, IBM enjoys "free cooling" using outside air temperature 63 percent of the year, resulting in a PUE of 1.3 rating. Electricity is only 4.5 US cents per kWh. The center also uses 1 Million KwH per year of wind energy.
The Raleigh data center is only 100,000 Square feet, with a PUE 1.4 rating. The Raleigh area enjoys 44 percent "free cooling" and electricity costs at 5.7 US cents per kWh. The Leadership in Energy and Environmental Design [LEED] has been updated to certify data centers. The IBM Boulder data center has achieved LEED Silver certification, and IBM Raleigh data center has LEED Gold certification.
Free cooling, electricity costs, and disaster susceptibility are just three of the 25 criteria IBM uses to locate its data centers. In addition to the 7 data centers it manages for its own operations, and 5 data centers for web hosting, IBM manages over 400 data centers of other clients.
It seems that Green IT initiatives are more important to the storage-oriented attendees than the x86-oriented folks. I suspect that is because many System x servers are deployed in small and medium businesses that do not have data centers, per se.