Originally posted by: TonyPearson

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.

1. 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.
   
2. 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.
   
3. 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.
   
4. 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.
   
5. 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.
   
6. 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 I/O group.
   
7. 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.
   
8. 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.
   
9. 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.
   
10. 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.
    
11. 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.
    
12. 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 automated solution.
    
13. 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.
    
14. 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.
    
15. Can I add or replace SVC nodes non-disruptively? Absolutely, see the Technotes [SVC Node Replacement page.


16. 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.

technorati tags: IBM, SVC, Audacity of Cope, svc_snap, Flamingo pink, Raven black, non-disruptive, svctools, AlphaWorks