Dedup problem


We are currently running Netapp Release and have turned on dedup on our cif's shares in an attempt to free up some disk space. Unfortunatly we have around 20 days worth of snapshots (to ease restoring of data for our helpdesk staff). I noticed that we have a 250gb snapshot with the name sis.41a470 etc. The volume itself is around 900gb with a snapshot reserve of 10% and i cant figure out what this snapshot actually is and if it is safe to get rid of it. We also run the scheduled sis dedup process once a night and that also seems to make no difference to the size of teh sis.41a snapshot.

Can anybody help?


Re: Dedup problem

Welcome to the forums!

A couple of thoughts come to mind on this one.  As you may already know, snap shot data is not deduped, only the active file system.  For that reason, I would make sure your schedules are set up to dedupe and then snapshot.  This will maximize dedupe savings.  This of course isn't always possible if you are taking snapshot more than once a day but it will help.

Second, since you are keeping 20 days, will that snap roll off the schedule eventually?  Do you have enough space to get you through until it does?

I tend to be in the "ain't broke, don't fix it camp" if the problem will fix itself in another few weeks.  If this is a manual snapshot then we need to take a look at what is in there.

Third, do you have snapshots exposed that users can see the .snapshot directory?  If so, you could always go in and take a look at the data and see what is eating up the space.  If you're not sure how to do that, let us know and we'd be happy to help!

Let us know and we'll take it from there.


Re: Dedup problem

Is your deduplication still running (check the sis status output)? The "sis"snapshot is only present during the initial scanning for data that can be deduplicated and will normally be automatically deleted.

Re: Dedup problem

thanks for the above replys but ive checked both

the snapshot appeared soon after i added the sis schedule (but was only tiny when i did this)

the normal snapshots for the drives are the default hourly.0 weekly.2 etc

this one has a name of sis.<a long id>(wont post here as im not sure what it converts to) but an example would be sis.414s54.523f3512.14124h and the snapshot is

/netapp.fv.volumes.snapshots.manage.RenameSnapShot?snapshot-old=sis.41a470c0-fafb-11db-9e3d-00a098041d7e&volume=HomeSep 18 17:13228.1 GB380.3 GBnormal

to explain in a bit more detail on what happened

we had a nightly snapshot which was just over 2 weeks old called nightly.14 and i deleted that manually (this was the 228gb snapshot) which as soon as i did that moved the space to the sis. snapshot which then made me think maybe i need to run sis start /vol/Home which i did and it made no diffence.

Problem being we only have around 15gb left on the volume and no space left on the aggr so i need to find a fix for this soon

Thanks for your help.

Re: Dedup problem

Ahhh, Sorry about that.  I didn't see the sis part in the name (it was early!).  So, that means it won't roll off on the schedule

and it is related to the dedupe scan as far as I can tell.

I'll have to pass on this one.  I'm hoping someone here has seen this otherwise I would open a case with NetApp pronto because it isn't a normal behavior.


Re: Dedup problem

Nnow that you are sure that dedupe is not active you can safely delete the snapshot.

There is a KB about this:

Re: Dedup problem

dedup is still running on the volume but idle at the moment (runs at midnight). Does that mean that this sis. snapshot can be deleted? what is contained in it?


Re: Dedup problem

The sis snapshot does not protect anything useful at the moment and iIt should have been deleted automatically. As the KB states, If sis is idle you can safely delete the snapshot.