Yeah....there's a way to scan the physical library and the VTL will create a
set of virtual tapes with the same barcodes as the physical
tapes....NetBackup will basically not know the difference and will treat
them the same.
I believe that you can always get the data off of the physical tapes if the
Nearstore dies. The problem would be if you had not gotten all of the data
transferred from the VTL to the physical tapes before the VTL gets hit with
some kind of failure.
The physical tapes would be used for off-siting. There is a "shadow copy"
feature that will keep stuff on the VTL until the disk space is needed for
new backups. So, if you have enough disk you can keep stuff online for
restores if needed.
If you are getting 30MB/sec to tape with vault/duplication, you're lucky.
I've found that it is highly dependent upon the image size and the makeup of
the image itself. If you have a number of small images, you will lower the
throughput of vault. Also, if you have a large image that is made up of a
number of small files, you will also impact the throughput. The best case
is a large image made up of large files.
Think of it this way....it's like having a couple of fire-hoses for the data
flow. One is coming into the media server from the VTL and the other is
out-bound to the physical tape drives. Vault/duplication does not allow you
to simply connect the fire-hoses. It has to empty the in-coming one and put
that data into buckets then empty those buckets into the out-going
fire-hose. Oh....and while it is filling the buckets, it's doing an audit
to ensure that you have the right number (counting the image fragments,
etc). The nearstore VTL will actually connect the fire-hoses and you get
line-speeds because it's doing the copy at a block-level to the physical
tapes.
As for the performance into the VTL, we don't really care, because there's
no shoe-shining with virtual drives. But we have seen very fast transfer
rates in and out depending upon the data source and the connection to the
media server. Like 30MB/sec or faster for single streams. And if you add
up the throughput of multiple streams for a given source, it's even faster
than that.
-stuart
-----Original Message-----
From: veritas-bu-bounces at mailman.eng.auburn.edu
[mailto:veritas-bu-bounces at mailman.eng.auburn.edu] On Behalf Of Paul Keating
Sent: Thursday, October 19, 2006 10:09 AM
To: veritas-bu at mailman.eng.auburn.edu
Subject: Re: [Veritas-bu] Data de-duplication solutions
So the Nearstore sees the physical tape library and directly copies fromthe
virtual tape cartridges, on a 1:1 basis to the physical carts?
How does the info get passed back to netbackup so Netbackup's catalogknows
what is on the physical tapes?
ie. if your Nearstore sc*ews the pooch, can you get your data off
thephysical tapes without importing them all?
Are your Nearstore vols replicated to a DR site? Or do you use
tapeexclusively for offsite DR?
For the record, I've been averaging well over 30MB/s tape to tape, usingLTO3
drives with LTO2 carts.
What kind of throughput are you getting "into" the nearstore during
yourbackups?
We're evaluating RFP responses for VTL at the moment.......
Paul
--
> -----Original Message-----> From:
veritas-bu-bounces at mailman.eng.auburn.edu >
[mailto:veritas-bu-bounces at mailman.eng.auburn.edu] On Behalf > Of Liddle,
Stuart> Sent: October 19, 2006 12:58 PM> To: T H;
veritas-bu at mailman.eng.auburn.edu> Subject: Re: [Veritas-bu] Data
de-duplication solutions> > > We are currently in the process of testing out
Direct Tape Copy on the> NetApp NearStore VTL's.> > The results we are
seeing is that we are getting better than > 50MB/sec with> LTO-3 drives
writing to LTO-2 tapes. We can attach up to 3 > drives per 2GB>
fiber-channel port. We figure we can do about 4TB/day per > drive or up to>
12TB/day for one NearStore VTL.> > Compare that to the very poor performance
of the > vault/duplication process> which we have found to be on the order
of roughly 11MB/sec or > about 1TB per> day per LTO-3 drive.> > We are still
testing and have not yet made the switch over to > this, but> right now it
looks very promising. If we do make the switch > we will not use> vault for
anything except for maybe container management.> >
--stuart====================================================================
================
La version fran?aise suit le texte anglais.
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