Which choice of volume collection sync for a windows file server?

[sbaldridge16]

I have a vSphere 5.1 Windows 2008 vm.  The O/S drive is a VMFS but it has two data drives which connect to a cs240 via iSCSI in the guest O/S.  In the cs240 array there are three volumes.

I need a sanity check on the best method to configure the volume collection.  I'd like to snapshot all three volumes at the same time and the synchronization options are none, vSphere, and MS VSS.  There are no applications installed on the Windows server.  Is my best choice "none"?  Perhaps I should choose "vSphere" since the o/s volume is a vSphere datastore, although the other two volumes are not?

Thanks for the help

Scott

[jliu79]

None is good for file server.

[rhellman18 · Accepted solution]

Jason is correct.  You should use the None option when specifying VSS Sync for these volumes.  All volumes in a volume collection will be snapped at the same time regardless of sync setting.  Synchronization simply refers to whether we're going to use VSS to get the underlying application to flush its data buffers and quiesce its disk activity.  Once synchronization is enabled for a volume collection, all volumes within the collection should be of the same type.  For instance, if you wish to sync with VMWare, all the volumes in the collection should be datastores.  Likewise, if your app is MS SQL you'll need to make sure the volumes are related to MSSQL.

The VSS mechanism is a bit strict.  In a nutshell we request a VSS enabled snap, The OS receives the request, does the needful and gives us the "go code".  We have 10 seconds from then to complete the required snaps.  Having too many volumes within a VSS enabled Volume Collection makes it difficult or impossible to complete snaps against all of them.  For this reason, we recommend the number of vss-enabled volumes per Volume Collection be kept as few as necessary to achieve the desired result.

[sbaldridge16]

Thanks for the helpful replies.

[jag880]

Could you help me understand why "none" is a good option? If it is a highly used file server wouldn't you want it quiesced to ensure data corruption doesn't occur? Since nimble is snapshoting it at a block level it is not entirely aware what is going on at the file system level. If users have data open couldn't corruption occur?

Thanks.