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Re: [Networker] de-duplication
2008-11-05 07:14:28
On 11/5/08 12:42 AM, tkimball wrote:
It may also be possible to use something like the Cypress (GreenBytes) NAS and
use its internal de-dup/compress for adv_file devices (over iSCSI). Networker
wouldn't know, or care.
http://green-bytes.com/cypress.html
Datadomain also plays in this space -- We have used their equipment for
several years now. The one gotcha with dedup is that you must write
your own scripts if you want to implement staging. Because of the
de-dup process, moving a 1TB saveset off the aftd to another medium will
not (or at least shouldn't) free up 1TB of space on the de-dup
appliance. I've asked EMC if their Avamar based de-dup product has
solved that issue -- no answer yet.
We're trying to get one here in order to test that theory, since it *may* be
able to replace the two *racks* of StorageTek Flex disk we use for adv_file
today (we have a Tier 4 DBO).
Of course, the sales folks got real silent when I mentioned using it in
environments with pre-compressed data (our Sybase dumps, which is about 20 TB
currently - about half the 'real' disk space of the Thumper chassis that
Cypress uses). I wanted to know how their de-dup extensions to ZFS would work
out here, since it was a proprietary change to the code.
Yeah, they should get quiet. Pre-compressed data should look different
every day -- there is very little chance (practical experience here with
datadomain devices and pre-compressed data) for pre-compressed data to
be de-dup'd or even compressed further at all. In general, compressing
compressed data makes it bigger.
--
Frank Swasey | http://www.uvm.edu/~fcs
Sr Systems Administrator | Always remember: You are UNIQUE,
University of Vermont | just like everyone else.
"I am not young enough to know everything." - Oscar Wilde (1854-1900)
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