Best practice for Exchange 2010 on ESXi 4.0 connecting to Equallogic SAN

bentleyforbes
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We just received our Equallogic SAN and are about to load new installations of Windows and Exchange server 2010.  My question comes in 2 main parts but mainly revolves around Snapshots.
What is the best way to do snapshots and the best way to configure the disks on the SAN

A. have the Exchange Database on a vhd handled by ESXi and snapshots done by Equallogic?
B. Exchange database handled via iSCSI on the Windows vm and use Equallogic Microsoft Exchange snap addin
C. some other config I haven't mentioned.
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Top Expert 2010

Commented:
May I ask why you are considering using snapshots? Snapshots are evil! :P Really, I recommend not using snapshots for much of anything. People tend to get the idea to use them for some sort of b/u solution, and they're not meant for that. If you do use them, use them solely when doing updates to your VM(s). Once the VM is updated and verified it's working as it should, commit (delete) the snapshot. Snapshots, even when committed (deleted) sometimes can 'hang' with a VM and not actually get committed to the VM, thus adding potential for VM corruption as well as continuing to grow and take up disk space. Use them only when/if needed.

That being said, what is your goal here with Exchange? What are you wanting to achieve?

Regards,
~coolsport00

Author

Commented:
I realize I left it a bit open, but the idea is to use Snapshots on the Equallogic SAN to replicate those to another Equallogic in another location for DR purposes.  We will be using the SAN also for fileserver and would be good to have snapshots of the files, but I'm wondering if having the OS and files and DBs in a VHD then the snapshots may not work correctly.  But again, its an Equallogic snaphsot, not the Vmware snapshot of the vhd. (though this might not make much of a difference)

Our idea was that if the main site went down, we would just start up the VMs at the DR site using the latest snapshot from the SAN.

I realize that Exchange 2010 has other ways of doing the DR with Active-Passive on 2 exchange servers, which could be a better solution anyways.
Top Expert 2010

Commented:
Ah...yes..forgot about SAN snaps..my apologies. That is a good way to go in a DR situation.

Author

Commented:
So SAN snaps are good, but should the ESXi host be doing the talking to the SAN or the Windows VM or does it matter?
I would think it would perform better if the ESXi was doing the iSCSI translation rather than the Microsoft iSCSI initiator.  And does Exchange need to be taken offline to do any of this?
Top Expert 2010

Commented:
Yes...SAN snaps are good.

I recommend ESXi directly to eliminate the OS overhead. It would be minimal but overhead nonetheless.

Last part I cant answer...sorry :-(
Top Expert 2014

Commented:
Generally if you're doing an Exchange aware snapshot then Exchange is taken offline automatically while it is done; it should only take a couple of seconds to quiesce the databases, take the snapshot, and bring Exchange back online so users shouldn't notice. VSS aware hardware snapshot providers should also tell Exchange that it's been snapped so that'll deal with the transaction log for you as well; non VSS/application aware snapshots don't tell Exchange it's been backed up so the t. log can get very big.

Author

Commented:
Andyalder...Yes I understand the benefits of a VSS aware snapshot, but will this work in a VM?
Specifically, will the hardware snapshot software work if the database is located within a VMDK?  Or will Exchange need direct access to the SAN?  or does it not matter?
Top Expert 2014
Commented:
I don't think VMware tells VSS that a snapshot has been taken, I was lead to believe VMware snapshots were dumb in that respect but I might be wrong. It'll work in a VM if the snap is made via RDM/EqualLogic but not if it's a VMDK snapshot as far as I've been lead to believe, but not an expert on that.

Author

Commented:
yeah, that's the tricky part.  We can use the Equallogic software, and then snap the whole volume which would be in a vmdk format, or have the Exchange server connect directly to the volume through it's own iSCSI initiator.  
But I think we can run the Equallogic exchange add-in and just snap the volume and have ESXi handling the iSCSI so it will in effect be in a vmdk but the logs will be parsed.
Top Expert 2010
Commented:
To answer your question about VSS...yes; it doesn't matter if the DB is a VMDK or RDM. It's all shown as a volume within the VM and is accessed the same way by b/u technologies.

Regards,
~coolsport00

Author

Commented:
I've closed this, and I think it will work, will definitely be trying this out next week.  Thanks for the comments.

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