IBM have offered Enterprise Storage Virtualization since June 2003 with the IBM SAN Volume Controller (SVC). October 2010 saw IBM releasing the Storwize V7000, taking the SVC code and packaging it into a midrange disk product. So now you have four possible choices:
- Use SVC to virtualize your storage.
- Use Storwize V7000 to provide internal SAS drives plus virtualize your storage.
- Use Storwize V7000 as a midrange disk product.
- Use Storwize V7000 virtualized behind SVC.
The great thing is that all four choices are valid and all four choices work just fine.
But for customers already using SVC, or considering SVC, the question then becomes, should I virtualize a Storwize V7000 behind an SVC? Does this makes sense?
The short answer: YES!
We have a great many customers happily doing this, so I thought I would share some common questions I get around configuration. Firstly there is an InfoCenter page on this which you will find here. Secondly there is a debate about whether we should create individual volume/arrays on the Storwize V7000 or just create a single pool on the Storwize V7000 (which equates to striping on striping). More bench marking is being done to see if one method is truly better than the other, so until then I recommend the method described below. If you have already done stripe on stripe, don't go changing anything until I update this post.
How many ports should I use for Zoning?
The Storwize V7000 has 8 Fibre Channel ports, 4 from each node canister. You need to zone at least two ports from each node canister to your SVC cluster. This is no different to how you would zone a DS5100 or an EMC VNX.
How will the SVC detect the Storwize V7000?
On the SVC you will see two storage controllers, one for each node canister. This is quite normal. The reason for this is that each node canister reports its own WWNN. This is not a problem and will not affect volume failover if one node canister goes offline.
In the example below the SVC has detected two new controllers. The confusing factor is that both report as 2145s, but they are a Storwize V7000. Rename them to reflect what they really are (something like StorwizeV7000_1_Node1 and StorwizeV7000_1_Node2).
How should I define the SVC on the Storwize V7000?
You need to create a new host on the Storwize V7000 and call it something like SVC_1. if the SVC WWPNs don't appear in the WWPN dropdown, you will need to manually add them as shown below:
You can get the SVC WWPNs from your existing zoning or by doing an svcinfo lsnodeagainst each SVC node or display them in the SVC GUI as shown below:
What size Storwize V7000 volumes should I create?
My recommendation is to do the following on the Storwize V7000
- Create arrays of preferably 8 disks in size. The ideal number will depend on how many disks you have. On my machine I have 22 disks, so I create three arrays each with seven disks (and one hot spare):
- Create one pool for each array:
- Create one volume out of each pool (using all space in the pool).
- Define the SVC to the Storwize V7000 as a host (as described above) and map all volumes to the SVC.
- On the SVC detect all the Storwize V7000 LUNs as MDisks and create one pool.
- Now you should have a pool on the SVC that you can use to create volumes to present to your hosts. They will be striped by default, which is exactly what you want.
Hopefully all of this makes sense. Questions and comments very welcome.