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Changing disk numbers in MS 2008 R2 Fail over cluster

Fred Blum
Regular Advisor

Changing disk numbers in MS 2008 R2 Fail over cluster

 

What circumstances can trigger the disk numbering in MS W2008 R2 to be changed? I have a 2 node MS W2008 R2 fail over cluster and found that the disk numbers between the 2 nodes have changed and is now no longer in sync. I am using pass tru disks for VMs and this can in case of a failover cause the wrong disks to be exposed to the VM.

 

We use iSCSI initiator and I have found that MS W2008 R2 screws up the favorite target list, possibly when it can not access the favorite target during start up. Issues might be IPv6 and IPv4 enabled on the SAN NIC (not in our case) or when network configuration has been updated/changed (our case added 2 NICs).

 

Way to fix the disk numbering?

 

Can the disk numbering be made pesistent? That under no circumstance it can change?

 

TIA,

 

Fred

 

 

 

 

 

 

 

 

2 REPLIES
Fred Blum
Regular Advisor

Re: Changing disk numbers in MS 2008 R2 Fail over cluster

 

After reading other posts on the internet the changing disk numbers seems to be default behavior in which case I can't believe windows would use the disk number to pass on as a disk identifier in case of a fail over or liveMigration. Would MS be so .....? 

It must be a unique iscsi identifier used in which case the database holding the disk no, iscsi id has become unstable. Are there tools for debugging this?

 

Fred

 

Fred Blum
Regular Advisor

Re: Changing disk numbers in MS 2008 R2 Fail over cluster

"In Windows Server 2008 failover clusters, the disk signature and the LUN ID are both used when identifying a cluster disk resource. If either of these has changed, the cluster configuration is updated. This translates into a reduction in the errors that are simply due to an attribute change on a physical disk resource."

 

So MS is not using the disk no to identify the resource. Are there tools to troubleshoout this? Comparing GUID and LUN ID between server nodes? Checking these against VM disk settings.

 

What can make a LiveMigration associate the wrong disk based on GUID/signature as this should never have happened.

 

Fred