Networker

Re: [Networker] new to Virtual Tape Library - what are the benefits?

2007-08-23 17:43:34
Subject: Re: [Networker] new to Virtual Tape Library - what are the benefits?
From: Darren Dunham <ddunham AT TAOS DOT COM>
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Date: Thu, 23 Aug 2007 14:40:13 -0700
> In a multi-storage-node environment, you will need to do a lot of
> provisioning and management that you simply don't have to do in the VTL
> world.  You have to figure out how big each AFTD must be, slice them up,
> then divvy them out using zoning and LUN masking.  Making them too big
> minimizes performance.  Making them too small increases management.
> Then when you need more, you have to add more, and you have to
> reconfigure your backup environment each time.  You just don't have
> these issues with a good VTL/IDT.

It really seems to be a matter of maturity.  When I was using a VTL
three years ago, I simply didn't trust the backup vendors own disk
storage solutions.  I think both Networker/NetBackup have gotten much
better, and I'm now more aware of the the problems that a VTL can create
all by itself.  I also like the fact that I'll probably be able to
upgrade to better features in the future.  Some of the VTL choices
require some hardware that I would have a difficult time repurposing.

> As to NW's ability to read and write AFTDs simultaneously, it's not
> something that really excites me.  It allows you start cloning each
> backup as soon as it's done, but you're going to have to script that.
> AND, if you make your virtual tapes 100 GB in size, you can fill one up
> in 30-60 mins with a transfer rate of 50-100 MB/s.  So you have to wait
> an hour before starting to clone each tape -- I don't see how that's
> going to impact anybody.  If you're asynchronously copying the tapes as
> they're filled, then this will cause a 1-hour delay at the beginning,
> but nothing the rest of the night.

If I could keep all my tapes streaming that fast, I probably wouldn't
care as much about VTLs.  :-)  One slow client or network problem that I
can't fix immediately can lead to a multi-hour backup job.  No
restores/clones from that volume while it's happening.  (Although if
you're not doing physical copies, micro-sizing the volumes will reduce
that problem).

-- 
Darren Dunham                                           ddunham AT taos DOT com
Senior Technical Consultant         TAOS            http://www.taos.com/
Got some Dr Pepper?                           San Francisco, CA bay area
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