Hi Folks: I''m wondering what is the correct flow when both raid5 and de-dup are enabled on a volume.... I think we should do de-dup first and then raid5 ... is that understanding correct? Thanks!
Hi Folks: I''m wondering what is the correct flow when both raid5 and de-dup are enabled on a storage volume.... I think we should do de-dup first and then raid5 ... is that understanding correct? Thanks!
On Mon, Apr 05, 2010 at 06:32:13PM -0700, Learner Study wrote:> I''m wondering what is the correct flow when both raid5 and de-dup are > enabled on a storage volume.... > > I think we should do de-dup first and then raid5 ... is that > understanding correct?Not really. Strictly speaking, ZFS doesn''t do raid5 - assuming you mean one of the raidz levels, pools can be created by assembling disks into one or more raidz groups. Dedup is then performed within the pool, and enabled at a dataset (filesystem) granularity. If you have raid5 in a san or hw controller, you might build a pool on top of the LUNs it presents, and again apply dedup within that pool. -- Dan. -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 194 bytes Desc: not available URL: <http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20100406/b8b3c740/attachment.bin>
Correct. Jeff Sent from my iPhone On Apr 5, 2010, at 6:32 PM, Learner Study <learner.study at gmail.com> wrote:> Hi Folks: > > I''m wondering what is the correct flow when both raid5 and de-dup are > enabled on a storage volume.... > > I think we should do de-dup first and then raid5 ... is that > understanding correct? > > Thanks! > _______________________________________________ > zfs-discuss mailing list > zfs-discuss at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Hi Jeff: I''m a bit confused...did you say "Correct" to my orig email or the reply from Daniel...Is there a doc that may explain it better? Thanks! On Mon, Apr 5, 2010 at 6:54 PM, jeff.bonwick at oracle.com <jeff.bonwick at oracle.com> wrote:> Correct. > > Jeff > > Sent from my iPhone > > On Apr 5, 2010, at 6:32 PM, Learner Study <learner.study at gmail.com> wrote: > >> Hi Folks: >> >> I''m wondering what is the correct flow when both raid5 and de-dup are >> enabled on a storage volume.... >> >> I think we should do de-dup first and then raid5 ... is that >> understanding correct? >> >> Thanks! >> _______________________________________________ >> zfs-discuss mailing list >> zfs-discuss at opensolaris.org >> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss >
On Mon, Apr 05, 2010 at 06:58:57PM -0700, Learner Study wrote:> Hi Jeff: > > I''m a bit confused...did you say "Correct" to my orig email or the > reply from Daniel...Jeff is replying to your mail, not mine. It looks like he''s read your question a little differently. By that reading, you are correct, because for a given write to a pool, the data will first be checked for dedup, and then the writes will be sent to the pool devices where raidz (or hw raid5) will be applied. I read the question as more about how to initally set up your pool (ie, as about a sequence of admin commands). Now you have answers for both, whichever you originally intended to ask. :)> Is there a doc that may explain it better?Several.. start with the ZFS FAQ and Best Practices Guide. -- Dan. -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 194 bytes Desc: not available URL: <http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20100406/80caee58/attachment.bin>
On Apr 5, 2010, at 6:32 PM, Learner Study wrote:> Hi Folks: > > I''m wondering what is the correct flow when both raid5 and de-dup are > enabled on a storage volume.... > > I think we should do de-dup first and then raid5 ... is that > understanding correct?Yes. If you look at the (somewhat outdated) ZFS Source Tour, you will see that the ZIO "layer" feeds I/Os to the VDEV "layer" which is where raidz is implemented. In ZIO, deduplication occurs after compression and checksumming but before space allocation. The checksum and physical size are used for the deduplication table key. -- richard ZFS storage and performance consulting at http://www.RichardElling.com ZFS training on deduplication, NexentaStor, and NAS performance Las Vegas, April 29-30, 2010 http://nexenta-vegas.eventbrite.com