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Wrapping up my week on All-Flash arrays, I thought I would cover some of the Enterprise Reliability features of the IBM FlashSystem.
On Monday, [IBM FlashSystem versus EMC XtremeIO all-Flash Arrays], I discussed some of the features of the IBM FlashSystem that differentiate it from EMC's ExtremeIO and other all-Flash arrays. On Tuesday, [IBM 2013 Storage Announcements for November 19] included discussion of the all-Flash model of the IBM System Storage DS8870 disk system.
Just as light bulbs burn out eventually after repeatedly being turned on and off, Flash does not last forever either.
A set of transistors can represent a single bit of informaiton (Single-level cell, or SLC for short), or multiple bits (Multi-level Cell, MLC). MLC typically refers to two bits, with a new "Triple-level cell" or TLC technology, able to store three bits per set of transistors.
SLC is faster and can endure more "Program-erase" write cycles, but MLC is less expensive to manufacture and therefore used in most consumer products, like digital cameras, smart phones, music players and USB memory sticks. To learn more on this, see this 6-page IBM whitepaper on [Comparison of NAND Flash Technologies Used in Solid-State Storage].
In between, "Enterprise MLC" (or eMLC for short) refers specifically to a different grade of chips IBM gets from the flash manufacturer. eMLC chips use a similar MLC bit arrangement, but are typically selected from higher bins, and most importantly have much longer program-erase cycle times which yield greater chip endurance, at the expense of long data retention when power is off (but seriously, when is anything off for very long in a data center?)
As a result, eMLC has 10x the endurance of regalar MLC, approaching parity with SLC at half the cost!
In the IBM FlashSystem, DRAM cache is used to buffer the writes first, then written out to the Flash. This helps to further improve the endurance.
For enterprise reliability, each Flash chip on the IBM FlashSystem has Error Correcting Codes (ECC), and then each set of 10 chips is placed in a 9+P RAID-5 configuration.
The chips are sub-divided into 16 planes. In the event a cell fails, the data for that plane can be reconstructed from parity, and written to spare space on the other planes of that same chip set. That plane is then reformated as an 8+P RAID-5, bypassing the failed plane.
In this manner, a cell failure only results in losing a small portion of one chip. If the same plane fails another failure on another chip, it will drop down to 7+P, 6+P, 5+P, and finally 4+P. This is known as "Variable Stripe RAID" or VSR for short.
IBM FlashSystem can survive over 1,000 such cell failures without an outage. By comparison, a single cell failure on an SSD often marks the entire drive as a failure.
But wait, there's more. Why stop at just RAID-5 across 10 chips. The chips are organized into modules, and IBM FlashSystem can perform RAID-5 across modules, in a 10+P+S RAID-5 configuration. This is referred to as "Two dimensional RAID" or 2D-RAID for short.
Even if you lost an entire module, the system will automatically rebuild on the spare module, and you can replace the bad one non-disruptively.
Many use cases for all-Flash arrays do not require such high levels of Enterprise reliability. Several of the all-Flash competitors have adopted a "des
The idea is to assume that the data stored on them is just a copy from some other storage media. In the event of a Flash failure, it can easily be restored from a mirrored copy or backup.
For the IBM FlashSystem, The newer 800 series are based on eMLC, ideal for the majority of business applications, databases and virtual machine images placed on all-Flash arrays. The older 700 series are based on more expensive SLC, designed specifically for sustained write-intensive workloads.
Within each series, the "tens" models (710, 810) offer RAID-0 striping across ECC and VSR protected modules. For higher levels of availability, the "twenties" models (720, 820) offer ECC, VSR and 2D-RAID protection.
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Wrapping up last week's theme on [New Year's Resolutions] to Eat Less and Exercise More. Yesterday, I talked about [tracking your diet], in this post, I will discuss tools to track your exercise and results.
(Note: I am neither a medical doctor nor registered dietician. I can share with you ideas that have worked for me, that might help you achieve your goals. I strongly suggest you read books and consult with medical experts as necessary.)
Back in 2009, studies found that [exercise alone does not lead to weight loss]. I had been working out at a gym, three times a week with a personal trainer, for six years, but was the same weight as when I started.
Much to the chagrin of my personal trainer, the article convinced me to quit the gym, discontinue her services, and focus on my diet instead. She warned I would gain 10 to 20 pounds within the year. Guess what? I didn't! I actually lost two pounds.
Here are my suggestions:
(FTC Disclosure: I work for IBM. I do not have any financial interest in, nor have been paid to mention any other companies, products or services on this blog post. Per FTC guidelines, this post can be considered a celebrity endorsement of cables from Startech.com, who provided me the cables at no charge.)
If you have resolved to lose weight, get fit, manage stress, or sleep better, and this series of posts has given you ideas or helped you in any way, I would love to hear about it. Please post a comment below!
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Well, it's Tuesday again, and you know what that means! IBM announcements!
Today, I am in New York visiting clients. The weather is a lot nicer than I expected. Here is a picture of the Hudson River through some trees with leaves turning color. Something we don't see in Tucson! Our cactus and pine trees stay green year-round!
The announcements today center around the IBM PureSystems family of expert integrated systems. The PureFlex is based on Flex System components. The Flex System chassis is 10U high that hold 14 bays, consisting of 7 rows by 2 columns. Computer and Storage nodes fit in the front, and switches, fans and power supplies in the back. Here is a quick recap:
IBM has sold over 1,000 Flex System and PureFlex systems, across 40 different countries around the world, since their introduction a few months ago in April! These latest enhancements will help solidify IBM's industry leadership,
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Every year, I teach hundreds of sellers how to sell IBM storage products. I have been doing this since the late 1990s, and it is one task that has carried forward from one job to another as I transitioned through various roles from development, to marketing, to consulting.
As you can see from this photo, Taipei is a large city with just row after row of buildings. The metropolitan area has about seven million people, and I saw lots of construction for more on my ride in from the airport.
The student body consists of IBM Business Partners and field sales reps eager to learn how to become better sellers. Typically, some of the students might have just been hired on, just finished IBM Sales School, a few might have transferred from selling other product lines, while others are established storage sellers looking for a refresher on the latest solutions and technologies.
I am part of the teach team comprised of seven instructors from different countries. Here is what the week entails for me:
These are the solution areas I present most often as a consultant at the IBM Executive Briefing Center in Tucson, so I can provide real-life stories of different client situations to help illustrate my examples.
To learn more about a Top Gun class in your area, see the [Top Gun class schedule].
The weather here in Taipei calls for rain every day! I was able to take this photo on Sunday morning while it was still nice and clear, but later in the afternoon, we had quite the downpour. I am glad I brought my raincoat!
technorati tags: IBM, Sales Training, Top Gun, Taipei, Taiwan, NAS, SONAS, disk, virtualization, unified+storage, SAN Volume Controller, SVC, Storwize V7000, Storwize V7000 Unified, Infrastructure Management, Tivoli Storage, Productivity Center, TPC, Unified Recovery Management, TSM, FlashCopy, FCM
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Well it's Tuesday again, and you know what that means.. IBM announcements! Today, IBM announces that next Monday marks the 60th anniversary of first commercial digital tape storage system! I am on the East coast this week visiting clients, but plan to be back in Tucson in time for the cake and fireworks next Monday.
Note that I said first commercial tape system as tape itself, in various forms, [has been around since 4000 B.C.]. A little historical context might help:
According to the IBM Archives the [IBM 726 tape drive was formally announced May 21, 1952]. It was the size of a refrigerator, and the tape reel was the size of a large pizza. The next time you pull a frozen pizza from your fridge, you can remember this month's celebration!
When I first joined IBM in 1986, there were three kinds of IBM tape. The round reel called 3420, and the square cartridge called 3480, and the tubes that contained a wide swath of tape stored in honeycomb shelves called the [IBM 3850 Mass Storage System].
My first job at IBM was to work on DFHSM, which was specifically started in 1977 to manage the IBM 3850, and later renamed to the DFSMShsm component of the DFSMS element of the z/OS operating system. This software was instrumental in keeping disk and tape at high 80-95 percent utilization rates on mainframe servers.
While visiting a client in Detroit, the client loved their StorageTek tape automation silo, but didn't care for the StorageTek drives inside were incompatible with IBM formats. They wanted to put IBM drives into the StorageTek silos. I agreed it was a good idea, and brought this back to the attention of development. In a contentious meeting with management and engineers, I presented this feedback from the client.
Everyone in the room said IBM couldn't do that. I asked "Why not?" The software engineers I spoke to already said they could support it. With StorageTek at the brink of Chapter 11 bankruptcy, I argued that IBM drives in their tape automation would ease the transition of our mainframe customers to an all-IBM environment.Was the reason related to business/legal concerns, or was their a hardware issue? It turned out to be a little of both. On the business side, IBM had to agree to work with StorageTek on service and support to its mutual clients in mixed environments. On the technical side, the drive had to be tilted 12 degrees to line up with the robotic hand. A few years later, the IBM silo-compatible 3592 drive was commercially available.
Rather than put StorageTek completely out of business, it had the opposite effect. Now that IBM drives can be put in StorageTek libraries, everyone wanted one, basically bringing StorageTek back to life. This forced IBM to offer its own tape automation libraries.
In 1993, I filed my first patent. It was for the RECYCLE function in DFHSM to consolidate valid data from partial tapes to fresh new tapes. Before my patent, the RECYCLE function selected tapes alphabetically, by volume serial (VOLSER). My patent evaluated all tapes based on how full they were, and sorted them least-full to most-full, to maximize the return of cartridges.
Different tape cartridges can hold different amounts of data, especially with different formats on the same media type, with or without compression, so calculating the percentage full turned out to be a tricky algorithm that continues to be used in mainframe environments today.
The patent was popular for cross-licensing, and IBM has since filed additional patents for this invention in other countries to further increase its license revenue for intellectual property.
In 1997, IBM launched the IBM 3494 Virtual Tape Server (VTS), the first virtual tape storage device, blending disk and tape to optimal effect. This was based off the IBM 3850 Mass Storage Systems, which was the first virtual disk system, that used 3380 disk and tape to emulate the older 3350 disk systems.
In the VTS, tape volume images would be emulated as files on a disk system, then later moved to physical tape. We would call the disk the "Tape Volume Cache", and use caching algorithms to decide how long to keep data in cache, versus destage to tape. However, there were only a few tape drives, and sometimes when the VTS was busy, there were no tape drives available to destage the older images, and the cache would fill up.
I had already solved this problem in DFHSM, with a function called pre-migration. The idea was to pre-emptively copy data to tape, but leave it also on disk, so that when it needed to be destaged, all we had to do was delete the disk copy and activate the tape copy. We patented using this idea for the VTS, and it is still used in the successor models of IBM Sysem Storage TS7740 virtual tape libraries today.
Today, tape continues to be the least expensive storage medium, about 15 to 25 times less expensive, dollar-per-GB, than disk technologies. A dollar of today's LTO-5 tape can hold 22 days worth of MP3 music at 192 Kbps recording. A full TS1140 tape cartridge can hold 2 million copies of the book "War and Peace".
(If you have not read the book, Woody Allen took a speed reading course and read the entire novel in just 20 minutes. He summed up the novel in three words: "It involves Russia." By comparison, in the same 20 minutes, at 650MB/sec, the TS1140 drive can read this novel over and over 390,000 times.)
If you have your own "war stories" about tape, I would love to hear them, please consider posting a comment below.