I have seen the minra option on the volume have a major affect on backup speed.  Have you got it set to minra=on on any of your volumes?

Cheers
Chris


----- Original Message -----
From: owner-toasters@mathworks.com <owner-toasters@mathworks.com>
To: Toasters <toasters@mathworks.com>
Sent: Fri May 09 16:02:14 2008
Subject: Max of 20MB/sec through FC attached LTO tape drive? Overland neo 2000

Asking here because we don't have current Overland support for the fibre
channel card and I would guess it is more of a problem with the card
rather than netapp (we only used the FCO with a netapp), but maybe
someone has encountered this...

Around 2004 we bought a Overland Neo 2000 tape library with the FCO VIA
scsi to FC converter board, and we got at most 20 or 25MB/sec through it
(per tape drive) depending if we were writing or reading.  This is both
with NDMP dumps from the filer disks to tape, and also across the
network into the filer to tape with NDMP.  The backup software is
Bakbone Netvault. Last year we tried attaching this library to a Unix
host directly with SCSI and our speed almost doubled.  I was floored,
and shocked that we spent so many years missing out on performance,
although 20-25 was the best I've seen anyone report for LTO2 so I never
expected more.

Recently we bought another Neo 2000 with LTO4 drives, and I decided to
move the FCO card over to it and try again, hoping maybe there was a
misconfiguration, but I could not find any and it still acts as if there
is a mystery cap on the speed of 20MB/sec (it averages 18-19 after it
gets going).  I've been all through the configuration of the FCO card
and it is set to 160M/sec per scsi bus, tried with and without domain
validation, and I even got the FC channel to operate at 2Gbit but no
improvement.  If I cannot figure this out then I will just attach it to
the Unix host with the other neo 2000, but its always nice to have more
options.  I would not bother operating a LTO4 drive at such a slow speed
in production because shoe-shining would probably wear it out and the
compression would be sub optimal or non-existent.

---

Christopher Holloway
Lead Consultant

Professional Services

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