Solved: SMVI - backing up VMs with iSCSI LUNS and SnapManager - Page 3

marcconeley · ‎2010-02-10

Is it possible to use SMVI v2 to perform VM consistent snapshots of VMs that have iSCSI LUNs mounted?

I am using vSphere (latest v) and SMVI v2. All my VMs are mounted on an NFS volume on my FAS2020.

All my Exchange, SQL and Sharepoint servers are using SnapManager for backups, and therefore have their data mounted on iSCSI initiator LUNs within the VMs.

Until recently I was creating hourly "non VM consistent" snaps and daily "VM consistent" snaps (according to: http://blogs.netapp.com/virtualization/2009/07/scheduling-smvi.html).

I encountered 2 main problems with this:

1) The daily VM consistent snapshots would always fail on 4-5 of my servers, randomly it seemed. The rest would snapshot OK.

2) I noticed that many of the volumes containing my iSCSI LUNs were rapidly filling up.

It seems that the random server snapshot failures all had 1 thing in common: they all had iSCSI LUNs (why sometimes they worked though, and sometimes not I have no idea!).

It also seems that by performing SMVI "VM consistent" snapshots of these servers, a conflict is caused with SnapManager which also results in the iSCSI LUN (mainly the SnapInfo one in the case of SQL!) being snapped. This happens outside of the control of SnapManager. So in my case, after 1 week my SnapInfo vol reported full - when I checked the snapshots on this vol I could see 7 days worth of SQL snaps (normal) - but also 7 days of additional SMVI snapshots!! (very bad).

This happened on normal VM servers with iSCSI LUNs mapped and my SQL servers.

Since then I read somewhere that VMware do not support VM snapshots of VMs with Microsoft initiated iSCSI LUNs (which rules out half my VMs!) and therefore I've removed these servers from my backup.

Is there any way around this problem?

Longer term my NetApp partner is currently selling me a backup project whereby we will snapshot all VMs and then snapmirror them to a remote site for DR. The problem is that my most important VMs have iSCSI LUNs. My understanding according to the above article is that VM consistent snapshots are important as the VM is quiesced and the snapshots are clean. Therefore my backup idea is not good as basically I'd be mirroring "dirty snapshots" to my remote DR site. Ideally these snapshots should be clean, VM consistent ones (or am I over valuing the importance of this?).

Help appreciated.

//Marc

watan · ‎2010-02-19

Hi Marc,

1)

Steps to configure the ESX SW iSCSI Software Initiator using VI-Client

    * Enable ESX iSCSI SW initiator in ESX server.
    * Check License under Licensed Features of Configuration Tab.
    * Add the VMKernel Port under the Networking configuration option. Enable      VMotion.
    * Under Security Profile select the port for the Software iSCSI client.
    * Select the ESX SW iSCSI initiator and click the "Enabled" checkbox.

Add ESX SW iSCSI targets to discovery list using VI-Client.

    * Navigate to the Properties of the iSCSI adapter and click on the Dynamic Discovery      tab.
    * Choose to Add new Target.
    * Enter the IP address & port of the target server and click OK.

2) If you're not having any specific problems with using MS iSCSI then I personally don't see any reason to change it. If its not broken...

Also refer to the following docs as they may have more on performance or general best practices.

The performance best practices :

For ESX 3.5: http://www.vmware.com/pdf/vi3_35/esx_3/r35u2/vi3_35_25_u2_iscsi_san_cfg.pdf

For ESX 4 : http://www.vmware.com/pdf/vsphere4/r40/vsp_40_iscsi_san_cfg.pdf

NetApp and VMware VI3 best practice Guide :

http://media.netapp.com/documents/tr-3428.pd

View solution in original post