Comments on: Practical Limits of NetApp Deduplication

By: kb.hurricane-ridge.com / Undoing A-SIS Deduplication

kb.hurricane-ridge.com / Undoing A-SIS Deduplication — Wed, 25 Mar 2009 18:22:36 +0000

[...] math to make sure you will have enough space in the fat volume once deduplication is undone. See my Practical Limits of NetApp Deduplication post elsewhere for more on this. Post a comment — Trackback URI RSS 2.0 feed for these [...]

By: Storage Short Take #4 - blog.scottlowe.org - The weblog of an IT pro specializing in virtualization, storage, and servers

Tue, 02 Dec 2008 13:01:14 +0000

[...] Leonard took up a concern about NetApp deduplication and volume size limits a while back. The basic gist of the concern is that in its current [...]

By: Storage Short Take #4 | Storage Blogs - Storage Monkeys Blogs

Storage Short Take #4 | Storage Blogs - Storage Monkeys Blogs — Tue, 02 Dec 2008 12:05:27 +0000

[...] Leonard took up a concern about NetApp deduplication and volume size limits a while back. The basic gist of the concern is that in its current [...]

By: Andy

Andy — Thu, 09 Oct 2008 18:26:57 +0000

Hi Larry,

Thanks for the comment, and the link to the updated document. However, I’m not sure that the situation I’m talking about changes (we’re haven’t upgraded from 7.2.4/7.2.4L1 yet): Where you run into the maximum deduplicated volume size, or know you will, and need to turn A-SIS off and run “sis undo” to grow the volume past that limit – the situation where you risk running into the following message on a 100% full volume:

[sis.undo.nospace:warning]: Undoing shared blocks on volume /vol/vol1 has aborted because there is insufficient free space. Data blocks that were still shared at the time the undo operation stopped will remain shared. Blocks already processed by the undo operation are no longer shared.

By: Larry Freeman

Larry Freeman — Thu, 09 Oct 2008 00:22:57 +0000

Good news Andy. A new version of TR-3505 (rev 5) has been released and volume limits have been restated. In your example, a FAS2050 with a 1TB volume, getting 50% dedupe savings and with 500GB of physical (deduped) data will not have to be resized, but in fact could grow to a logical size of 16TB. On page 19: “The maximum shared data limit per volume for deduplication is 16TB, regardless of the platform type. Once this limit is reached, there is no more deduplication of data in the volume, but writes to the volume continue to work successfully until the volume gets completely full.” I am sorry this was not communicated very clearly in earlier versions of TR-3505 and we made sure to clarify this in Rev 5.

As far as raising the hard volume limits for dedupe, we tried like the devil to get this into 7.3 but had some technical hurdles we just couldn’t clear in time for that release. I’ve taken a vow of silence when discussing unannounced deudpe enhancements, but rest assured that we want to raise vollume limits too and an announcement will be forthcoming.

Here is the link to the Rev 5 TR-3505 http://communities.netapp.com/docs/DOC-1642 on the NetApp dedupe community, it will also be posted soon on http://www.netapp.com in the technical library.