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SMVI Snapshots on VMDK that is NOT part of Backup job

Posted on 2012-03-26
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Last Modified: 2012-04-02
We have two VMs:

VM1:
Located in Datastore 1
Has one VMDK located in Datastore3

VM2:
Located in Datastore 2
Has one VMDK located in Datastore3 as well.

The purpose for the VMDK located in datastore 3 is to NOT capture the contents of the VMDK in the SMVI backups. Only Datastore 1 and 2 have backups run against them.

I'm noticing that snapshots are accumulating in Datatsore3 from both Datastore1 and Datastore2. How is this possible?

While looking at datastore 3's snapshots I see the following:

smvi_datastore1_daily_recent...
smvi_datastore2_daily_recent....
smvi_datastore1_daily...
smvi_datastore2_daily....
.....
....

The backup jobs in NetApp VSC are run against the Datastores. What ended up happening is the drives that were created in Datastore3 were created as Thin Provisioned. Curious as to why this is since the default is Thick. The snapshots quickly ate into the free space and both VM's froze when it hit 100%.

Any ideas?
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Question by:MMRNLA
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by:IanTh
ID: 37770552
snapshots are a delta of the vmdk not a full copy

thin provisioned means it grows as required starts small
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Expert Comment

by:IanTh
ID: 37770555
its probably because they are thin provisioned and have a snaphot associated with them
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Assisted Solution

by:Andrew Hancock (VMware vExpert / EE MVE^2)
Andrew Hancock (VMware vExpert / EE MVE^2) earned 200 total points
ID: 37770588
Snapshots are used by Third Party Backup tools to backup and Virtual Machines.

If you have Virtual Machines that are running on Snapshots are the Backup has been processed I would contact the vendor, as this should not happen, you virtual machines should not be left running omn snapshots.


A snapshot is NOT a backup of a VM; that is a gross misconception.

A snap shot is a way to preserve a point in time when the VM was running OK before making changes. A snapshot is NOT a way to get a static copy of a VM before making changes.  When you take a snapshot of a VM what happens is that a delta file gets created and the original VMDK file gets converted to a Read-Only file.  There is an active link between the original VMDK file and the new delta file.  Anything that gets written to the VM actually gets written to the delta file.   The correct way to use a snapshot is when you want to make some change to a VM like adding a new app or a patch; something that might damage the guest OS. After you apply the patch or make the change and it’s stable, you should really go into snapshot manager and delete the snapshot which will commit the changes to the original VM, delete the snap, and make the VMDK file RW. The official stance is that you really shouldn’t have more than one snap at a time and that you should not leave them out there for long periods of time. Adding more snaps and leaving them there a long time degrades the performance of the VM.  If the patch or whatever goes badly or for some reason you need to get back to the original unmodified VM, that’s possible as well.  

I highly recommend reading these 2 articles on VMware Virtual Machine Snapshots:

Understanding Snapshots - http://kb.vmware.com/kb/1015180
Snaphot Best Practices - http://kb.vmware.com/kb/1025279

Also check out the following Snapshot Articles by Eric Siebert

Pt.1- http://is.gd/Lajg4p
Pt.2- http://is.gd/NdKQWC
Pt.3- http://is.gd/tp2vEK
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Assisted Solution

by:coolsport00
coolsport00 earned 300 total points
ID: 37770886
Well, it's good to tell about snaps, but no one has really answered your question. Why are the snapshots in DS3? Hard to say. If you're running a 3rd party VM backup, chances are that is the cause of the problem. If you have TWO VMDKs per VM...a system volume (VMDK) and a data volume (VMDK) of some kind, typically, snapshots are KEPT WITH THE VM. Meaning, if you created a VM on DS1 (along with the system volume VMDK), then that's where snaps are stored. 3rd party VM b/u solutions take snapshots of all VMDKs, unless you explicitly exclude ancillary (data) volumes from the backup. I use Veeam and for a few of my VMs, that's what I do (exclude disks that is). It's hard to tell from your post, but it kinda sounds like you're only running a b/u against the system volume of your 2 VMs? Why you're seeing snaps on DS3 is hard to say. The only answer I can suggest is that your 3rd party b/u solution is doing so. I would recommend getting with your vendor to verify since I've not heard of nor used what you're using for VM b/u's.

~coolsport00
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Author Comment

by:MMRNLA
ID: 37770987
The backup we use is NetApp Snap Manager for VI.

coolsport00, thanks for the response. I have no idea why everyone is talking about snapshots..  I know it was late when I posted but I think i got my point across.

=)
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ID: 37770990
those snapshots are linked to the SAN Snapshots, daily recent etc
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Expert Comment

by:coolsport00
ID: 37770991
What is this VMDK on DS3? Is it 1 per VM, just 1, or what?...
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by:MMRNLA
ID: 37771029
We currently use an application that replicates data over the WAN. It requires about 70GB's of hard drive space for a "spool". The SnapManager for VI backups were picking these spool drives up as large deltas which inflated our nightly snapshots.

So the idea here was to create a separate datasore that is not being backed up. We then added new virtual disks to the VMs but stored them on this new datastore instead of local to the VM.

By doing this the nightly backup should ignore the contents of the virtual disk that's located on the new datastore since the backup is done at a datastore level.

Sounds confusing.. hope I was clear.
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by:coolsport00
ID: 37771069
Ok..that's kinda what it sounded like; and yes...you're right...it "should" ignore that DS. The files you listed above aren't traditional named snaps for vSphere VMDKs. They're usually shown as 0000x.VMDK/0000x-delta-VMDKs, etc. @hanccocka mentions SAN snapshots. Are you using those?
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by:MMRNLA
ID: 37771086
Our SAN is a NetApp FAS3420. We use their product called SnapManager for VI which intergrates with Virtual Center for backing up the VMs. When you setup the backup job it gives you the option of either backing up the VMs by datastore, or at the VM level.

We backup at the datastore level.

This product tags snapshots with the "smvi_.." prefix,
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LVL 119
ID: 37771093
@cool.... SMVI Leverages SAN Snapshots and interfaces into the VMware Storage API to create VMware Snapshots, to ensure the guests are correctly quiecsed
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by:coolsport00
ID: 37771094
Then it sounds like @hanccocka is spot on :)
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LVL 119
ID: 37771098
before the SAN snapshotbis completed.
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LVL 119
ID: 37771100
SMVI is really a bunch of scripts with an interface.
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Accepted Solution

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MMRNLA earned 0 total points
ID: 37777873
Figured out my issue. NetApp SnapManager for VI (VSC) by default will backup VMs and all of their VMDKs regardless of where they are located, even in my case with VMDKs residing on multiple datastores.

Within the backup job in the VSC console, you have to go to the "Spanned Entities" tab and uncheck the alternate datastore on which the VMDK resides that you don't want backed up.

DS1
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LVL 119
ID: 37777882
that should resolve it.
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by:coolsport00
ID: 37777959
Hmm...similar to Veeam & what I suggested in #37770886 a little. Glad it's taken care of...

~coolsport00
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Author Closing Comment

by:MMRNLA
ID: 37795137
I resolved my own issue
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