Array Performance and Data Protection

Re: Nimble Software Snapshot Size

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Occasional Contributor

Nimble Software Snapshot Size

In the new software I cannot see the size of a volume snapshot like in previous versions.  Am I missing something in the location of this information or has this information been removed in the new version.  Doesn't make much sense to not be able to see the size of your snapshots.

Valued Contributor

Re: Nimble Software Snapshot Size

Try Monitor -> Capacity, then type the volume name in the "Filter by volume" at left pane...

You can get snapshot usage per volume as below:

Valued Contributor

Re: Nimble Software Snapshot Size

Slightly frustrating that you don't have the snapshot view like on the older NOS release

Respected Contributor

Re: Nimble Software Snapshot Size

Hello Mark,

Good point! Just created an RFE for this, there are a few frustrations with the new GUI that need to be ironed out.

Many thanks,


Honored Contributor

Re: Nimble Software Snapshot Size

The snapshot size is also shown in the main view of the volume itself...

I'm speculating here, but my hunch is that the reason why it was most likely was removed is that the older view actually misrepresented the size the snapshot actually was.

If you attend a recent NTS course it's explained in a bit more detail - however the total snapshot usage part is the true space used. The per-snap size that is shown actually is showing you the amount of new data written to the volume since the snap was created, not the size of the snapshot itself.

It was confusing a lot of people and didn't actually mean a lot - hence why I suspect it was stripped out.

Nick Dyer
twitter: @nick_dyer_

Re: Nimble Software Snapshot Size

You can still get it via the CLI using snap --list --vol vol_name, which does show "New Data" per snapshot, I was also sad to see it was removed from the GUI.


Re: Nimble Software Snapshot Size

That's exactly right, Nick!
The snapshot usage and snapshot new data are 2 completely different concepts. New Data is not a presentation of the usage of the snapshot.When new data is written to volume, if volume is still referencing the blocks, it takes the precedence in reporting of those blocks in usage. This is a shared block architecture.

Let's say that 1TiB of data is written to volume and all writes stop. Take a snapshot. Snapshot "New Data" will report as 1TiB. Snapshot usage is 0MiB because volume is still referencing all those blocks. Write 5TiB more to volume, stop writes. Take another snapshot. Snapshot "New Data" in second snapshot will be 5TiB, while usage is still 0MiB, volume will report all of 6TiB of usage. Now, delete 3TiB of data from volume, no new writes, take a snapshot. 3rd snapshot will show 3TiB "New Data" and 2nd snapshot will have 3TiB of data usage, volume will now report 3TiB data used as well.

The reason why "snap --list" still reports "New Data" is because it is used for calculation of replicated data. However, in majority of situations Administrators are interested in snapshot usage, not the New Data since the last snapshot.


Re: Nimble Software Snapshot Size

It sure would be nice to show the amount of data that has been changed at a per snap level.  We used to be on Equallogic and trying to figure out why snapshot space was consumed was difficult.  That is why we switched to nimble only to lose this with the 4.x upgrade.  Why do to storage admins need to see per snap usage vs total?

With many VMs on a volume, you may have snapshot space grow very quickly during some time periods versus others.  If I knew that the snapshot space between 9pm and 11pm grew 100%.  I can then check out those vms to see what the heck is going on to cause so much change on a volume.  A good example is some server admin enabled defrag on a vm every night at 10pm or someone decided to open an attachment that is wiping out the files on your file server.

Knowing how much data changes is important and size of snapshots helps understand how our business changes data, when.





Regular Visitor

Re: Nimble Software Snapshot Size

You can use the PowerShell toolkit for this. The following example produces a nice, per snapshot size report. You could script this with parameters to make it useful:

PS> Get-NSSnapshot -vol_name 'Datastore02' | select name, @{n="CompressedGB";e={"{0,12:N1}" -f ($_.new_data_compressed_bytes /1gb) }}, @{n="UncompressedGB";e={"{0,14:N2}" -f ($_.new_data_uncompressed_bytes /1gb) }}