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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Continuing my week in Chicago, for the IBM Storage Symposium 2008, we had sessions that focused on individual products. IBM System Storage SAN Volume Controller (SVC) was a popular topic.
SVC - Everything you wanted to know, but were afraid to ask!
Bill Wiegand, IBM ATS, who has been working with SAN Volume Controller since it was first introduced in 2003. answered some frequently asked questions about IBM System Storage SAN Volume Controller.
Do you have to upgrade all of your HBAs, switches and disk arrays to the recommended firmware levels before upgrading SVC? No. These are recommended levels, but not required. If you do plan to update firmware levels, focus on the host end first, switches next, and disk arrays last.
How do we request special support for stuff not yet listed on the Interop Matrix?
Submit an RPQ/SCORE, same as for any other IBM hardware.
How do we sign up for SVC hints and tips? Go to the IBM
[SVC Support Site] and select the "My Notifications" under the "Stay Informed" box on the right panel.
When we call IBM for SVC support, do we select "Hardware" or "Software"?
While the SVC is a piece of hardware, there are very few mechanical parts involved. Unless there are sparks,
smoke, or front bezel buttons dangling from springs, select "Software". Most of the questions are
related to the software components of SVC.
When we have SVC virtualizing non-IBM disk arrays, who should we call first?
IBM has world-renown service, with some of IT's smartest people working the queues. All of the major storage vendors play nice
as part of the [TSAnet Agreement when a mutual customer is impacted.
When in doubt, call IBM first, and if necessary, IBM will contact other vendors on your behalf to resolve.
What is the difference between livedump and a Full System Dump?
Most problems can be resolved with a livedump. While not complete information, it is generally enough,
and is completely non-disruptive. Other times, the full state of the machine is required, so a Full System Dump
is requested. This involves rebooting one of the two nodes, so virtual disks may temporarily run slower on that
What does "svc_snap -c" do?The "svc_snap" command on the CLI generates a snap file, which includes the cluster error log and trace files from all nodes. The "-c" parameter includes the configuration and virtual-to-physical mapping that can be useful for
disaster recovery and problem determination.
I just sent IBM a check to upgrade my TB-based license on my SVC, how long should I wait for IBM to send me a software license key?
IBM trusts its clients. No software license key will be sent. Once the check clears, you are good to go.
During migration from old disk arrays to new disk arrays, I will temporarily have 79TB more disk under SVC management, do I need to get a temporary TB-based license upgrade during the brief migration period?
Nope. Again, we trust you. However, if you are concerned about this at all, contact IBM and they will print out
a nice "Conformance Letter" in case you need to show your boss.
How should I maintain my Windows-based SVC Master Console or SSPC server?
Treat this like any other Windows-based server in your shop, install Microsoft-recommended Windows updates,
run Anti-virus scans, and so on.
Where can I find useful "How To" information on SVC?
Specify "SAN Volume Controller" in the search field of the
[IBM Redbooks vast library of helpful books.
I just added more managed disks to my managed disk group (MDG), can I get help writing a script to redistribute the extents to improve wide-striping performance?
Yes, IBM has scripting tools available for download on
[AlphaWorks]. For example, svctools will take
the output of the "lsinfo" command, and generate the appropriate SVC CLI to re-migrate the disks around to optimize
performance. Of course, if you prefer, you can use IBM Tivoli Storage Productivity Center instead for a more
Any rules of thumb for sizing SVC deployments?
IBM's Disk Magic tool includes support for SVC deployments. Plan for 250 IOPS/TB for light workloads,
500 IOPS/TB for average workloads, and 750 IOPS/TB for heavy workloads.
Can I migrate virtual disks from one manage disk group (MDG) to another of different extent size?
Yes, the new Vdisk Mirroring capability can be used to do this. Create the mirror for your Vdisk between the
two MDGs, wait for the copy to complete, and then split the mirror.
Can I add or replace SVC nodes non-disruptively? Absolutely, see the Technotes
[SVC Node Replacement page.
Can I really order an SVC EE in Flamingo Pink? Yes. While my blog post that started all
this [Pink It and Shrink It] was initially just some Photoshop humor, the IBM product manager for SVC accepted this color choice as an RPQ option.
The default color remains Raven Black.
Continuing my week in Chicago, for the IBM Storage Symposium 2008, I attended two presentations on XIV.
XIV Storage - Best Practices
Izhar Sharon, IBM Technical Sales Specialist for XIV, presented best practices using XIV in various environments.He started out explaining the innovative XIV architecture: a SATA-based disk system from IBM can outperformFC-based disk systems from other vendors using massive parallelism. He used a sports analogy:
"The men's world record for running 800 meters was set in 1997 by Wilson Kipketer of Denmark in a time of 1:41.11.
However, if you have eight men running, 100 meters each, they will all cross the finish line in about 10 seconds."
Since XIV is already self-tuning, what kind of best practices are left to present? Izhar presented best practicesfor software, hosts, switches and storage virtualization products that attach to the XIV. Here's some quickpoints:
Use as many paths as possible.
IBM does not require you to purchase and install multipathing software as other competitors might. Instead, theXIV relies on multipathing capabilities inherent to each operating system.For multipathing preference, choose Round-Robin, which is now available onAIX and VMware vSphere 4.0, for example. Otherwise, fixed-path is preferred over most-recently-used (MRU).
Encourage parallel I/O requests.
XIV architecture does not subscribe to the outdated notion of a "global cache". Instead, the cache is distributed across the modules, to reduce performance bottlenecks. Each HBA on the XIV can handle about 1400requests. If you have fewer than 1400 hosts attached to the XIV, you can further increase parallel I/O requests by specifying a large queue depth in the host bus adapter (HBA).An HBA queue depth of 64 is a good start. Additional settings mightbe required in the BIOS, operating system or application for multiple threads and processes.
For sequential workloads, select host stripe size less than 1MB. For random, select host stripe size larger than 1MB. Set rr_min_io between ten(10) and the queue depth(typically 64), setting it to half of the queue depth is a good starting point.
If you have long-running batch jobs, consider breaking them up into smaller steps and run in parallel.
Define fewer, larger LUNs
Generally, you no longer need to define many small LUNs, a practice that was often required on traditionaldisk systems. This means that you can now define just 1 or 2 LUNs per application, and greatly simplifymanagement. If your application must have multiple LUNs in order to do multiple threads or concurrent I/O requests, then, by all means, define multiple LUNs.
Modern Data Base Management Systems (DBMS) like DB2 and Oracle already parallelize their I/O requests, sothere is no need for host-based striping across many logical volumes. XIV already stripes the data for you.If you use Oracle Automated Storage Management (ASM), use 8MB to 16MB extent sizes for optimal performance.
For those virtualizing XIV with SAN Volume Controller (SVC), define manage disks as 1632GB LUNs, in multiple of six LUNs per managed disk group (MDG), to balance across the six interface modules. Define SVC extent size to 1GB.
XIV is ideal for VMware. Create big LUNs for your VMFS that you can access via FCP or iSCSI.
Organize data to simplify Snapshots.
You no longer need to separate logs from databases for performance reasons. However, for some backup productslike IBM Tivoli Storage Manager (TSM) for Advanced Copy Services (ACS), you might want to keep them separatefor snapshot reasons. Gernally, putting all data for an application on one big LUNgreatly simplifies administration and snapshot processing, without losing performance.If you define multiple LUNs for an application, simply put them into the same "consistencygroup" so that they are all snapshot together.
OS boot image disks can be snapshot before applying any patches, updates or application software, so that ifthere are any problems, you can reboot to the previous image.
Employ sizing tools to plan for capacity and performance.
The SAP Quicksizer tool can be used for new SAP deployments, employing either the user-based orthroughput-based sizing model approach. The result is in mythical unit called "SAPS", which represents0.4 IOPS for ERP/OLTP workloads, and 0.6 IOPS for BI/BW and OLAP workloads.
If you already have SAP or other applications running, use actual I/O measurements. IBM Business Partners and field technical sales specialists have an updated version of Disk Magic that can help size XIV configurations fromPERFMON and iostat figures.
Lee La Frese, IBM STSM for Enteprise Storage Performance Engineering, presented internal lab test results forthe XIV under various workloads, based on the latest hardware/software levels [announced two weeks ago]. Three workloadswere tested:
Web 2.0 (80/20/40) - 80 percent READ, 20 percent WRITE, 40 percent cache hits for READ.YouTube, FlickR, and the growing list at [GoWeb20] are applications with heavy read activity, but because of[long-tail effects], may not be as cache friendly.
Social Networking (50/50/50) - 50 percent READ, 50 percent WRITE, 50 percent cache hits for READ.Lotus Connections, Microsoft Sharepoint, and many other [social networking] usage are more write intensive.
Database (70/30/50) - 70 percent READ, 30 percent WRITE, 50 percent cache hits for READ.The traditional workload characteristics for most business applications, especially databases like DB2 andOracle on Linux, UNIX and Windows servers.
The results were quite impressive. There was more than enough performance for tier 2 application workloads,and most tier 1 applications. The performance was nearly linear from the smallest 6-module to the largest 15-module configuration. Some key points:
A full 15-module XIV overwhelms a single SVC 8F4 node-pair. For a full XIV, consider 4 to 8 nodes 8F4 models, or 2 to 4 nodes of an 8G4. For read-intensive cache-friendly workloads, an SVC in front of XIV was able to deliver over 300,000 IOPS.
A single node TS7650G ProtecTIER can handle 6 to 9 XIV modules. Two nodes of TS7650G were needed to drivea full 15-module XIV. A single node TS7650 in front of XIV was able to ingest 680 MB/sec on the seventh day with17 percent per-day change rate test workload using 64 virtual drives. Reading the data back got over 950 MB/sec.
For SAP environments where response time 20-30 msec are acceptable, the 15-module XIV delivered over 60,000 IOPS. Reducing this down to 25,000-30,000 cut the msec response time to a faster 10-15 msec.
These were all done as internal lab tests. Your mileage may vary.
Not surprisingly, XIV was quite the popular topic here this week at the Storage Symposium. There were many moresessions, but these were the only two that I attended.
Well, it's Tuesday again, and that means IBM announcements!
We've got a variety of storage-related items today, so here's my quick recap:
DS5020 and EXP520 disk systems
[IBM System Storage DS5020]
provides the functional replacement for DS4700 disk systems. These are combined controller
and 16 drives in a compact 3U package.
The EXP520 expansion drawer provides additional 16 drives per 3U drawer. A DS5020 can
support upo to six additional EXP520, for a total of 112 drives per system.
The DS5020 supports both 8 Gbps FC as well as 1GbE iSCSI.
New Remote Support Manager (DS-RSM model RS2)
The [IBM System Storage DS-RSM Model
RS2] supports of up to 50 disk systems, any mix of DS3000, DS4000 and DS5000 series.
It includes "call home" support, which is really "email home", sending error alerts to IBM
if there are any problems. The RSM also allows IBM to dial-in to perform diagnostics before
arrival, reducing the time needed to resolve a problem. The model RS2 is a beefier model
with more processing power than the prior generation RS1.
New Ethernet Switches
With the increased interest in iSCSI protocol, and the new upcoming Fibre Channel over
Convergence Enhanced Ethernet (FCoCEE), IBM's re-entrance into the ethernet switch market
has drawn a lot of interest.
The [IBM Ethernet Switch r-
series] offers 4-slot, 8-slot, 16-slot, and 32-slot models. Each slot can handle either
16 10GbE ports, or 48 1GbE ports. This means up to 1,536 ports.
The [c-series] now offers a
24-port model. This is either 24 copper and 4 fiber optic, or 24 fiber optic.
The "hybrid fiber" SFP fiber optic can handle either single or multi-mode, eliminating the
need to commit to one or the other, providing greater data center flexibility.
The [IBM Ethernet Switch B24X]
offers 24 fiber optic (that can handle 10GbE or 1GbE) and 4 copper (10/100/1000 MbE RJ45)
Storage Optimization and Integration Services
[IBM Storage Optimization and
Integration Services] are available. IBM service consultants use IBM's own
Storage Enterprise Resource Planner (SERP) software to evaluate your environment and provide
recommendations on how to improve your information infrastructure. This can be especially
helpful if you are looking at deploying server virtualization like VMware or Hyper-V.
As people look towards deploying a dynamic infrastructure, these new offerings can be a
Over on his Backup Blog, fellow blogger Scott Waterhouse from EMC has a post titled
[Backup Sucks: Reason #38]. Here is an excerpt:
Unfortunately, we have not been able to successfully leverage economies of scale in the world of backup and recovery. If it costs you $5 to backup a given amount of data, it probably costs you $50 to back up 10 times that amount of data, and $500 to back up 100 times that amount of data.
If anybody can figure out how to get costs down to $40 for 10 times the amount of data, and $300 for 100 times the amount of data, they will have an irrefutable advantage over anybody that has not been able to leverage economies of scale.
I suspect that where Scott mentions we in the above excerpt, he is referring to EMC in general, with products like
Legato. Fortunately, IBM has scalable backup solutions, using either a hardware approach, or one purely with software.
The hardware approach involves using deduplication hardware technology as the storage pool for IBM Tivoli Storage Manager (TSM). Using this approach, IBM Tivoli Storage Manager would receive data from dozens, hundreds or even thousands
of client nodes, and the backup copies would be sent to an IBM TS7650 ProtecTIER data deduplication appliance, IBM TS7650G gateway, or IBM N series with A-SIS. In most cases, companies have standardized on the operating systems and applications used on these nodes, and multiple copies of data reside across employee laptops. As a result, as you have more nodes backing up, you are able to achieve benefits of scale.
Perhaps your budget isn't big enough to handle new hardware purchases at this time, in this economy. Have no fear,
IBM also offers deduplication built right into the IBM Tivoli Storage Manager v6 software itself. You can use sequential access disk storage pool for this. TSM scans and identifies duplicate chunks of data in the backup copies, and also archive and HSM data, and reclaims the space when found.
If your company is using a backup software product that doesn't scale well, perhaps now is a good time to switch over to IBM Tivoli Storage Manager. TSM is perhaps the most scalable backup software product in the marketplace, giving IBM an "irrefutable advantage" over the competition.
Back in June, I mentioned this blog was [Moving to MyDeveloperWorks] which is based on IBM Lotus Connections.
Finally, the move is complete for all bloggers. If you are having problems with the redirects, you might need to unsubscribe and re-subscribe in your RSS feed reader. Here are the new links for several IBM bloggers that have moved over: