Let me know if you remember the abbreviation.
About dedupe and trust, read the article comments to this posting by W Curtis Preston:
http://www.backupcentral.com/mr-backup-blog-mainmenu-47/13-mr-backup-blog/271-dedupe-to-tape-crazy.html
HTH
Robyn
--- In commvault < at > yahoogroups.com ([email]commvault%40yahoogroups.com[/email]), "Paul Hutchings" <paul.hutchings < at > ...> wrote:
I don't think the option I was discussing with the pre-sales guy is SILO though, it has some other abbreviation but I forget what it is now.
In terms of whether using deduped aux is a good idea, my concerns aren't so much around time (as you say that's a matter of policy and testing) but more around data integrity - is there any greater risk of not being able to do a restore from tape if the data is deduped.
I know there shouldn't be, but dedupe is still relatively new technology (proven by the fact that Commvault claim to be the only vendor that lets you put dedupe data on tape).
-----Original Message-----
From: commvault < at > yahoogroups.com ([email]commvault%40yahoogroups.com[/email]) on behalf of teq_nomad
Sent: Tue 05-Apr-11 3:57 PM
To: commvault < at > yahoogroups.com ([email]commvault%40yahoogroups.com[/email])
Subject: [commvault] Re: Diabolical Aux Copy Performance?
Hi Erik, Paul,
I haven't played with this, however, rehydrating to tape is the default whereas sending the deduped data to tape is SILO.
Just so happens there a sample online from the Technical Reference Library which nicely spells out the crux of choice your making
"Consider the following when configuring the deduplication store:
- Larger deduplication stores provide better deduplication benefits and higher space savings. However, very large deduplication stores increases data dependency within silo storage, and might affect Silo storage performance.
- Smaller deduplication stores translates to less number of media accessed for data retrieval providing faster restore operations and better manageability of Silo Storage data"
http://services.commvault.com/library/samples/SiloStorageTrainingReference.pdf
So, there's a play-off between dedupe savings and restore times. I would say you need to ask your business how many degrees of disaster they want to cover with which "time to recover". If none of your tapes are deduped, then are you sure you will always have an online copy somewhere that will restore faster, and that your system will never have a gmail-style incident which will corrupt all online copies.
I think I'd be doing some restore tests for starters, so that you could make a recommendation to your mgt.
Anyway, hope you enjoy the SILO reading.
Robyn
--- In commvault < at > yahoogroups.com ([email]commvault%40yahoogroups.com[/email]), "erlarson2000 < at > ..." <erlarson2000 < at > > wrote:
I cant wait to hear replies. We rehydrate to tape also and also see much slower speeds than I would expect going to tape. Have been thinking about keeping data deduped from disk to tape since we moved to cla licensing but haveny had time to do it yet. Thanks for raising the question.
Sent from my Verizon Wireless Phone
----- Reply message -----
From: "Paul Hutchings" <paul.hutchings < at > >
Date: Tue, Apr 5, 2011 3:47 am
Subject: [commvault] Re: Diabolical Aux Copy Performance?
To: <commvault < at > yahoogroups.com ([email]commvault%40yahoogroups.com[/email])>
Thanks, that looks like it may have a lot of potential. I do intend to
go to 9.0, as it stands I suspect I may be going with SP1B due to the
timescales.
I would be interested in peoples views on whether it's actually worth
doing rehydrated aux copies to tape or whether it's sane to simply aux
copy deduped data directly to tape?
My Media Agent is standalone from the primary SAN infrastructure, and
with D2D w/dedupe I should be able to keep a good month's worth, if not
more (hard to know until we're backing up full production volumes) on
maglib.
I'm thinking that in a DR situation I'm not likely to be hitting tapes
as I'd have to have lost my primary SAN and the MA/maglib, and in the
typical "Can I get this file/folder back from six months ago?", is it
really an issue to have to wait a little longer whilst it's restored
from tape and rehydrated? (that's rhetorical and the answer is "No").
Appreciate any thoughts.
Paul
From: commvault < at > yahoogroups.com ([email]commvault%40yahoogroups.com[/email]) [mailto:commvault < at > yahoogroups.com ([email]commvault%40yahoogroups.com[/email])] On
Behalf Of mcgillcanberra
Sent: 04 April 2011 23:30
To: commvault < at > yahoogroups.com ([email]commvault%40yahoogroups.com[/email])
Subject: [commvault] Re: Diabolical Aux Copy Performance?
You could get some benefit from upgrading to V9 and defining this reg
key on the MAs: DataMoverUseLookAheadLinkReader. This reads ahead the
aux copy data using a separate thread.
Docco here:
http://documentation.commvault.com/commvault/release_9_0_0/books_online_
1/english_us/features/registry_keys/registry_keys.htm#DataMoverUseLookAh
eadLinkReader
and here:
http://documentation.commvault.com/commvault/release_9_0_0/books_online_
1/english_us/features/single_instance/single_instance.htm#Look-Ahead_Log
ic
Craig.
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