I'm not convinced either. Although our numbers are a little different,
you and I end up roughly at the same place. There are a number of
vendors whose de-dupe targets top out at about 200-300 MB/s, which is
roughly the speed of 2-3 LTO-3 drives, depending on how well you use
them. If you need more than that, you need to buy another box. (BTW,
Data Domain's numbers have increased to about 200 MB/s.)
These numbers work just fine when we're talking backups via the LAN to
LAN-based backup servers. You're going to need at least two, possibly
three network-based backup servers to generate 200 MB/s. Assuming 70
MB/s or so per master/media server, you buy one de-dupe unit per three
master/media servers or so. You can scale pretty far that way. You
will need to make sure that backup A is always sent to de-dupe unit A,
and backup B is always sent to de-dupe unit B, and so on. (If you send
backup B to de-dupe unit A after initially sending it to de-dupe unit A,
its first backup will not get de-duped against anything, resulting in a
significant decrease in overall de-duplication ratio.) While you won't
get as big of a de-dupe ratio as you would if you could have a single
device that could do 1000s of MB/s, there is an argument to be made that
you won't get much de-dupe when de-duping the backups of server A
against those of server B -- unless they have similar data. So a very
large setup like this will require a bit of planning, but I think the
benefits outweigh the extra planning required.
Now, if you happen to have a SINGLE SAN media server that needs MORE
than 200 MB/s, then you're going to want a device that can handle that
level of throughput. This is going to be a pretty big server, BTW, as a
200 MB/s device can back up about 6 TB in 8 hours. And notice I said
SAN media server, not a regular media server, as a regular media server
isn't going to be able to generate more than 200 MB/s, as it's getting
its backups via IP. But a SAN media server is backing up its own data
locally, so it can go much faster. This also means you're really
looking at a SAN/block device, which means you're really looking at a
VTL. (Yes, I'm aware of the Puredisk storage unit around the corner. I
think you'll find it's not going after this part of the market.)
If you need this kind of throughput, there are a few products that are
advertising several hundred or thousands of MB/s within a single de-dupe
setup. These are the newer kids on the de-dupe block, of course, so
they're not going to have as many customer references as the vendors
that have been selling de-dupe as long. But from what I've seen,
they're worth a look.
---
W. Curtis Preston
Backup Blog @ www.backupcentral.com
VP Data Protection, GlassHouse Technologies
-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Ed Wilts
Sent: Monday, September 24, 2007 9:44 PM
To: 'Clem Kruger'; dave.markham AT fjserv DOT net; 'Jeff Lightner'
Cc: veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Tapeless backup environments?
I'm not convinced that writing to a DataDomain is going to be faster
than
writing to multiple LTO-3 drives over a SAN. The DD is limited to about
90MB/sec which is on par with 1-2 LTO-3 drives and not much more than
that.
Unless, of course, you consider adding extra DD units for every 2 LTO-3
drives you currently have and that's going to bump your costs up even
higher
(which might be offset by the requirement for a Decru FC520 encrypting
appliance for every 2-3 LTO-3 drives today).
I don't think that NetBackup 6.5 includes de-duplication. It's provided
by
PureDisk which is a separately licensed product. With 6.5.1, you'll be
able
to use PureDisk as a storage unit, something that's not there yet today.
.../Ed
--
Ed Wilts, RHCE, BCFP, BCSD
Mounds View, MN, USA
mailto:ewilts AT ewilts DOT org
> -----Original Message-----
> From: veritas-bu-bounces AT mailman.eng.auburn DOT edu [mailto:veritas-bu-
> bounces AT mailman.eng.auburn DOT edu] On Behalf Of Clem Kruger
> Sent: Monday, September 24, 2007 11:32 AM
> To: dave.markham AT fjserv DOT net; Jeff Lightner
> Cc: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: Re: [Veritas-bu] Tapeless backup environments?
>
> Hi Dave,
>
> Yes it is a difficult decision I have looked at DataDomain with
> NetBackup. I have found that the backups are faster and there is a
vast
> amount of disk being saved.
>
> NetBackup 6.5 includes de-duplication and I have become a great friend
> of it. To use the words of a supplier, "Saving me Time, Saving me
Space
> and Saving me Money" :)
>
>
> Kind Regards,
> Clem Kruger
>
> -----Original Message-----
> From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
> [mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Dave
> Markham
> Sent: 24 September 2007 17:35 PM
> To: Jeff Lightner
> Cc: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: Re: [Veritas-bu] Tapeless backup environments?
>
> Guys i've just read this thread and can say im very interested in it.
> The first thing is i learned a new term called deduplication which i
> didn't know existed.
>
> Question : I gather Deduplication is using other software. DataDomain
i
> think i saw mentioned. Where does this fit in with Netbackup and does
> the software reside on every client or just a server somewhere?
>
> Ok, so im trying to kit refresh a backup environment for a customer
> which has 2 sites. Production and DR about 200 miles apart. There is a
> link between the sites but the customer will probably frown on
> increased
> bandwidth charges to transfer backup data across for DisasterRecovery
> purposes.
>
> Data is probably only 1 TB for the site with perhaps 70% being
required
> to be transfered daily to offsite media.
>
> Currently i use tape and i was just speccing a new tape system as i
> thought by using disk based backups, and retentions of weekly/monthly
> backups lasting say 6 weeks, im going to need a LOT of disk, plus the
> bandwidth transfer costs to DR site
>
> LTO3 tapes are storing 200gb a tape which is pretty good compared to
> disk i thought.
>
> I guess in my set up its a trade off between :-
>
> Initial cost of disk array vs initial cost of tape library, drives and
> media
>
> Time take to backup ( network will be bottle neck here. Still on
100Meg
> lan with just 2 DB servers using GigaBit lan to backup server.
>
> Offsite transfer of tapes daily to offsite location vs Cost of
> increased
> bandwith between sites to transfer backup data.
>
>
> Im now confused what to propose :)
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