VMware Solutions Discussions

SMVI and Virtual Mode RDMs

I have a VM which is running SQL Server 2005 and has the following disks:

C:     30GB     VMDK     datastore1

😧     500GB     RDM     "Virtual Mode"     datastore2

E:     10GB     VMDK     datastore1

OS/program files is on C: and SQL databases, program files and DB dumps are located on drive 😧

How does SMVI handle backing up Virtual Mode RDMs? I read that it doesn't work with physical mode but wasn't sure about virtual.

Should all of the disks be in the same ESX datastore? Otherwise I think this VM is going to get snapped twice and we could have to recover two different datastore/volumes for SFR.

P.S. SMSQL is not an option unfortunately.             


Re: SMVI and Virtual Mode RDMs


It's a tad complex story.

First & foremost, if you want to do VSS-assisted application-consistent snapshots, then be wary of this:

http://www.netapp.com/us/library/technical-reports/tr-3737.html, page 28

"All application data needs to be contained on virtual disks (VMDKs) in NFS or VMFS datastores,
and not on RDMs or LUNs that are accessed using the Microsoft iSCSI Software Initiator in the
guest OS."

(plus have a look at the table on page 30)

Here is an interesting thread about using SMVI only vs. SMVI + SnapManager products:




Re: SMVI and Virtual Mode RDMs

Thanks for the reply.

Yeah, I checked out tr-3737 and the table on page 30 you refer to says "physical mode" RDMs. "Virtual Mode" RDMs (what I have) are a little different animal since VMware can take a snapshot of them -- and since that is the case, I figure why wouldn't it work with SMVI then? I searched tr-3737 for "virtual mode" and got 0 results..it seems to only reference physical mode.

What I'm aiming for here is "guest/file system level consistency"...not really application level. We are taking care of the SQL application backups via flat file dumps...so if I get the file system consistent, I've got what I need for this case.

Re: SMVI and Virtual Mode RDMs

I know that physical mode RDM is a must for SnapDrive / SnapManager environment (SD doesn't support virtual mode RDMs).

This isn't quite clear for me whether virtual mode RDM will actually cause any trouble for SMVI to work.

Personally I'd probably split SQL database from dumps into different drives - you can leave the former outside of SMVI, keep the latter as plain VMDK & back it up using SMVI.


Re: SMVI and Virtual Mode RDMs

I agree with Radek there. And you make a very good point about virtual mode RDM's. We will update the documentation with this as well.



Re: SMVI and Virtual Mode RDMs

SMVI and SDW will not work on virtual mode RDM's. We will updatet the documentation with this information.



View solution in original post

Re: SMVI and Virtual Mode RDMs

Thanks Amrita.

Just for my knowledge and better understanding of the product/technology, why will virtual mode RDMs not work with SMVI? If VMware can take a snapshot of it, I thought SMVI would be ok then. The VM in question which has it does not have SDW installed.

Any plans to make virtual RDMs compatible in a future version? Sure would be nice


Re: SMVI and Virtual Mode RDMs

I guess it was design decision which was taken not to support virtual RDM's. I can definitely take this down as a requirement.



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