Veritas-bu

[Veritas-bu] Ethernet Bottleneck - need design suggestions

2002-12-18 21:09:47
Subject: [Veritas-bu] Ethernet Bottleneck - need design suggestions
From: turk182 AT chipware DOT net (Chip Paswater)
Date: Wed, 18 Dec 2002 18:09:47 -0800
> > So the connection from the Server to the library is not the bottleneck.  I
> > have 4 drives going down 1 fibre path and 4 down the other.  Considering
> > 1gb FC can do 100MB/sec, and an LTO drive does 15MB/sec, that means a max
> > througput of 60MB/sec per FC port.
> 
> Minor correction: that's the uncompressed speed.  If you're doing
> compression on your drives, which you should be, you could theoretically
> push that up to 120mB/sec.  Realistically I've seen LTO drives hit
> 20mB/sec each.  Also, the SBUS cards on the E4000's aren't known for the
> best throughput so they could be part of your problem.

Should I turn on compression in Veritas as well as using drive compression?
Or should I use one or the other.  If so, which one?  I would assume drive
compression only, but wouldn't compression from within Netbackup give me
compression over my already taxed ethernet link?

> > So how do I scale the solution to open the ethernet bottleneck?  Veritas is
> > not being forthcoming with a solution, and I can't seem to find any best
> > practices documents on their site with any insight.
> 
> This is just the sort of thing SSO was designed to handle.  You don't have
> to put all of your large servers on the SAN and make them media servers as
> long as they're all served by gigabit ethernet.  You could pick another
> machine or two to make media servers or, if you want to keep the load off
> of your production machines, buy a new box just for this purpose.  Each
> tape drive can only talk to one media server at a time, but if your
> master/media is backing up 5 hosts, your new media server could be backing
> up 5 more or whatever.

> If you have any specific questions let me know.  I work for a storage
> integrator/reseller so this is what I do for a living.  I've seen quite a
> number of installations where the LTO drives are not native fiber and they
> work quite well.  Until about eight or ten months ago LTO and fiber were a
> bad combination due to instability, lack of interoperability, etc , but it
> has come a long way since then.  Our LTO installs are rock solid even with
> fiber/SCSI bridges.

Thanks Jason, this makes perfect sense.  Sounds like what I need to do is
let the e4000 drive 4 of the drives, and go out and buy a couple of dual
proc e220's to drive the other 4 drives.  These e220's would use the SSO
drives but the e4000 would control the robot for all 8 drives.