NetApp Dedupe an RDM or alternative?

EE,

vol 2.5TB (300gb free and space guranteed)
LUN 2.0TB (RDM full) (space reserve)
Snap Reserve 10% = 250gb?

Our LUN went offline when the vol got full. After deleting snaps by turning on autodelete, we now have 85% capacity according to df -h. Just enough for the dedupe staging process/logs exc.

So should I enabled dedupe or just manage snaps better? I had 10% snap reserve so I thought that would be 250GB (our vol has 300GB free) so I thought I was safe unless snap reserves are allowed to overcommit?


RDMs are essentially reserved. I spent two hours trying to read this Dedupe document attached but was confused on whether or not an RDM would benefit me with the settings you see above. pg.45 6.4.18
Dedupe-tr-3505.pdf
snyderkvAsked:
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Paul SolovyovskySenior IT AdvisorCommented:
Snapshots can and will grow beyond snap reserve as this is just used for accounting purposes, it is not a hard limit.  The autodelete i is based on volume so the snapshots are deleted when space on volume become an issue versus space in snap reserve
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Paul SolovyovskySenior IT AdvisorCommented:
From best practice documents you should not enable snap reserve on Netapp volumes with LUNs.  (keep in mind that snap reserve is just used for accounting so they'll work the same way)

Dedupe enable - depends on what type of data in the LUN.  For instance Exchange LUNs don't dedupe very well but LUNs with windows shares work great.

With respect to space management:  Make sure you manage your LUNs, ensure that you perform space reclaimation via snap drive since the Netapp is filer and emulates block the LUN will become fragmaneted if there are writes/deletes and we have seen customers run out of space on the NEtapp volume with backup LUNs that have a lot of data added and deleted frequently..

Review your configuration and make changes accordingly.
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robocatCommented:
snapshot autodelete and volume autogrow are 2 essential ways to make sure the volume doesn't fill up.

Use of a tool like Operations Manager (DFM) can also help to monitor volumes. It will send warning e-mails before the volume is full.

Dedupe is a space efficiency tool, not a space management tool.  If you're strained for storage, it can help in some cases. Otherwise just make sure there's more free space in the volume.
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snyderkvAuthor Commented:
Paul,

If it's a best practice to not enable snap reserve on a Netapp Volume with a LUN, then what would snap reserve be enabled on? All NetApp has is LUNs within Volumes. Sorry for the confusion

And I believe I was told that you can only use snap drive with NFS?  We are using FC/iSCSI type environment as a theatre wide standard.
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snyderkvAuthor Commented:
Robocat,

Volume autogrow, wouldn't the Volume just keep growing in that case until it uses all the space in the aggr?

Nobody is watching vol/aggr size in this environment, it's not like this perfect little corporate desk job you picture, it's high turnover, high speed, low skill work environment.

We set the Vol to space guarantee so it doesn't expand and shut down the aggr on us and kill all the volumes.
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Paul SolovyovskySenior IT AdvisorCommented:
On Netapp volumes with LUNs (FC/ISCSI) snapshot reserve should be set to zero.  With CIFS/NFS you should use snapshot reserve as it provides actual volume size (for instance a 500GB volume with 10% snapshot reserve for cifs will show a 450GB volume)
 If you don't use snapshot reserve for CIFS the data increase in the volume may come from data increase for actual data or data stored by snapshot and by looking at the volume you will not know where the data is coming from
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robocatCommented:
Autogrow also has a limit on how much % it can grow.

If the app is business critical, you should look into an automatic monitoring tool like OM.
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snyderkvAuthor Commented:
Paul, If we can't run snapshot reserve on volumes with FC/iSCSI, then how do we recover to an old snapshot? Do you  have a link to where you found this information? I did not see it in the document I linked.

Rob, It's military, they won't buy another product unless someone sells it to them and I'm not a sales men. I'd rather keep my taxes lower anyways. We already have enough junk floating around with nobody using them. Not enough personnel, contracts or skill to add another piece of software. I don't think the answer is to add more software, it's to set things up correctly the first time and make things automated as possible.

So just to try and get an answer and close the question, is snap reserve allowed to go over the 10% or 5% that I set in the volume if I don't delete old snaps or set autodelete?
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Paul SolovyovskySenior IT AdvisorCommented:
Let me clarify.  You can still configure the volume with snapshots, just set the snapshot reserve to zero.  Snapshot reserve is just used for accounting to show how much space your snapshots are taking up (think a of a divider) but it doesn't stop you from taking snapshots.  

With Netapp volumes that have LUNs the only difference is that you set the snapshot reserve to zero but leave the snapshot schedule in place (typically snapmanager for sql, exchange, etc..)  Still set the volume for autodelete, that will not change either.
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snyderkvAuthor Commented:
Paul,

Gotcha, I thought the snap reserve % was a hard set limit saying "I don't want snapshots to go beyond this % of my volume space"

You're saying this is incorrect thinking?

We use snap schedules, but we don't use snapmanager for exchange anymore since their was no personnel or skilled workers and training to use and manage it.
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snyderkvAuthor Commented:
Thanks
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