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StrongLiang
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questions about snapshot

(my first post here. please lemme know if this is not the right place)


I have a few questions about snapshot after reading a bunch of KB articles:


http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=102527...

- "Use no single snapshot for more than 24-72 hours."

Most of my snapshots live for a long time and I haven't noticed any problem. I don't understand why such suggestion.


http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=101316...

- "In this example, the process took approximately 64 seconds…"

This sounds like taking a snapshot on a production server could be a risky business, is it true?


http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=100330...

- I see that there is consolidate option on vSphere and it also tells you whether a VM needs it or not, but what are the criterion? I understand that if one deletes a snapshot, the content of the delta link gets consolidated into the parent disk, but when do you need to perform consolidate without delete?

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BenLiebowitz
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When you create a snapshot, a delta VMDK is created for each VMDK. These delta VMDKs can grow as large as the provisioned size of its VMDK. The problems come from having free space on the datastores. The longer a snapshot is around, the longer it can take to commit the changes when you delete it. Also, to commit the changes, you need to have enough free space on the datastore equal to the provisioned space of the VM itself.

I've also seen snapshots become corrupt after staying around a long time. Also, the more snapshots stored with a VM, the higher the chance for corruption.

I've handled environments with lots of snapshots and it was rough. I had VMs become corrupt and have to be restored from backups on a regular basis.

I avoid them when I can.

Backup software is a better bet. Like Veeam!

Ben Liebowitz, VCP vExpert 2015, 2016, & 2017 If you found my post helpful, please mark it as helpful or answered to award points.

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BenLiebowitz
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When you create a snapshot, a delta VMDK is created for each VMDK. These delta VMDKs can grow as large as the provisioned size of its VMDK. The problems come from having free space on the datastores. The longer a snapshot is around, the longer it can take to commit the changes when you delete it. Also, to commit the changes, you need to have enough free space on the datastore equal to the provisioned space of the VM itself.

I've also seen snapshots become corrupt after staying around a long time. Also, the more snapshots stored with a VM, the higher the chance for corruption.

I've handled environments with lots of snapshots and it was rough. I had VMs become corrupt and have to be restored from backups on a regular basis.

I avoid them when I can.

Backup software is a better bet. Like Veeam!

Ben Liebowitz, VCP vExpert 2015, 2016, & 2017 If you found my post helpful, please mark it as helpful or answered to award points.
vThinkBeyondVM
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I agree with Ben on not keeping snapshots for long time.

There is cost on snapshot creation, but over the releases, it is getting faster. However we should make sure that when to use snapshot and how to maintain the same.

I suggest you to go through this blog post :http://www.vladan.fr/vmware-snapshots-explained/

also this :http://www.yellow-bricks.com/2010/07/05/changes-to-snapshot-mechanism-delete-all/


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StrongLiang
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special thanks to the links. the videos are very useful to me.

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Manky
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Hi Vicky,

Thanks for the video link. I am fairly new to vmware. It helped a lot. Smiley Happy

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