Question about PowerPath Migration Enabler for Windows 2008 Clusters

You are reading it correctly. The basic difference between Windows 2003 Clusters and Windows 2008 Clusters is that Windows 2003 Clusters are dependent on disk signatures - whereas Windows 2008 are dependent on GUIDs. This necessitates the difference between the 2 ways of commiting the changeover.

Thankyou

Sam Claret EMC OSAPI WIndows TSEIII

Thanks Sam.

Another quick question for you.  In the same document it says to "move all failover groups to the active node" and says to shut down the other nodes in the cluster.

If my cluster has multiple cluster services running and I plan on doing a migration on only one, do I still have to fail all groups to a single node and shut the other nodes down?  And if I do, is it still required to restart all services during powermig commit, or just the one where the migration took place?

I think I can sell taking the momentary outage to restart the individual cluster service, but if I have to shut down every single one of them in this cluster just to migrate one, I don't think that will fly.  It would also be beneficial for me if I could leave the remaining services running on the other nodes while the single service is running on the node that is performing the migration.

This step applies to PPME-migrated devices.

That is helpful information.  The only other thing I need to know is if just the resource group being migrated needs to be restarted or if all resource groups must be restarted.

Thanks.

Thanks for the information.  I will report back after my migrations to let the forums know how they went.  My steps will be as follows:

1.  Assign target disks to all cluster nodes

2.  Assign all resource groups to a single node and shut down the remaining nodes

3.  Use PowerPath Migration Enabler Host Copy to perform the migration on LUNs in a single resource group

4.  Shut down only the resource group whose drives were migrated

5.  Run powermig commit

6.  Restart the resource group that was part of the migration

7.  Bring up the other cluster nodes and reassign resource groups appropriately

Please add step 5a.

Run powermig cleanup.

You want to ensure that the source device is no longer available in case of a cluster failover.

If you have multiple applications running across the cluster hardware and you only want to migrate one set of devices for one application, you "could" unmask just those devices from all but one of the cluster nodes.  That way, you wouldn't necessarily have to shut everything down.  Today, that is not an officially supported migration method for PPME.  I would recommend speaking with your EMC representative about an RPQ for this.  The RPQ is a request for a non-standard configuration.

Everything was successful with our PPME migration on a SQL 2008 cluster.  The only outage was the momentary shutdown of the failover groups to run powermig commit.

We did have an issue on a subsequent migration on a non-cluster machine.  We decided to try a migration from a thick LUN to a thin LUN (Clariion thin pool).  When we ran the powermig setup command to put the source and target into a session, the target LUNs (the thin ones) went into an "unreadable" state according to Windows Disk Management.

So this new problem is probably for a new post, but the original SQL 2008 migrations were successful thanks to all of your help.

Glad to hear that it went well.  With regards to the other item that you noted, this is a known issue when new disks are added to the host.  Here is an excerpt from the PowerPath for Windows Release Notes:

"On Windows Server 2008, disks are marked offline when first added to the host. The user must manually enable these offline disks before they can be used."

I hope this helps.

It's actually not that the disks are "offline", but they are listed as "unreadable".

We assigned the new disks and manually enabled them.  Up until this point everything was okay, the operating system was seeing them fine.  We initialized them as basic disks.

The problem occurred when we ran powermig setup.  As soon as the PPME session was created, the disks reported as "unreadable" in Disk Management, even though PowerPath is reporting 4/4 paths available with no errors.

If the PPME session is deleted, the disks return to a readable state.

We have a case open with EMC to investigate.  I'm assuming it has something to do with them being thin LUNs.  This is the only difference from our previously successful migrations.

This is what I thought as well, but when we started the migration the host crashed.

I was tying the "unreadable" to the crash, but perhaps the unreadable note is normal behavior when the target LUN is locked and the crash was related to something else.

I see.  When you kick off a PPME session with the setup, the target device is not accessible to prevent device access.  I believe that this is what you are seeing.When the migration is complete, the device would be usable again.

I have a simple 2008r2 two node cluster used for file sharing. I failed/migrated all processes to a single node and shut down the other. Now I have a single server running all the services. No problem. I plan on using PPME to move the data from one CLARiiON to another. I have successfully used PPME on standalone 2008r2 servers without any problems. But I'm confused about step #4 above. Please excuse my ignorance but what is a "resource group"? In the "Failover Cluster Manager" I can't find any "resource group" to shut down? I will attempt to attach a screen shot of what I see.

Thank you.

-Brian