Veritas-bu

[Veritas-bu] RE: Veritas-bu digest, Vol 1 #1051 - 14 msgs

2002-03-14 18:50:12
Subject: [Veritas-bu] RE: Veritas-bu digest, Vol 1 #1051 - 14 msgs
From: anaseem AT vanhosp.bc DOT ca (Atif Naseem)
Date: Thu, 14 Mar 2002 15:50:12 -0800
Hello There.
Thanks for the hints on my question of performance issues where i was getting 
more through put on network as compared to local backups. I got the solutions 
and now my local backups are fast as compaerd to network backups.
Couple of days back , by mistake i configure that DLT 8000 drive as DLT2 , but 
later on i removed the storage unit and install it back as DLT. Some how the 
volume in the tape drive still thinks it si Type 2 cartdrige. I just erase the 
volumes on that cartdrige , remove it from the drive and add it back. After 
doing this small exercise , DLt tape drive recognize it as the correct density 
cartdrige. In my setup i have two different scsi buses for my tape drive and 
disks so no point of scsi bottleneck in my case.
thanks again
atif


--------------------------------------------------------------
Atif Naseem
Unix Consultant 
Vancouver General Hospital
anaseem AT vanhosp.bc DOT ca
-----------------------------------------------------

>>> "Paul Bleimeyer" <paulb AT mayo DOT edu> 03/14/02 11:53AM >>>
Atif,

I would try and see if you have another scsi interface/channel available,
separating the disks and tape drive. You didn't mention what scsi card you
are using or if it's an internal adapter, but the typical issue I see with
this, is that the scsi channel you are using may be slowing down to the
speed of the slowest device on the chain. In your case this is most likely
the DLT8000. So, if your disks are transferring at only 10mb per sec, and
that's max throughput at the lowest speed device on the scsi chain, then
they may not be able to keep the buffers full on the tape drive. A low tech
way to determine this would be to watch the drives and tape unit during a
test full backup and see if the drive see-saws or stop/starts in a pattern
close the disk activity lights. In any event, I tend to favor having tape
devices on a separate interface anyways. Maybe I am old school here, but you
might test this out and see if you don't see an immediate improvement with a
separate channel in the mix. Keep us posted on your resolution.

Regards,

Paul

Disclaimer: The opinions expressed in this email reflect the personal
opinion of the author above and in no way should be considered a
recommendation from my company or employer.

Atif Naseem writes:
> I am testing the backup speed on the network as compared to local . I am
getting bit strange results.
> I have master server (E250 450MHZ 256 RAM - solaris 8 Netbackup 3.4 data
center) having DLT8000 . the Other machine (Sun 220 R , 750Mhz dual
proceesor with 1G Ram - Solaris 8)  is on the network acting as media server
plus some oracle databases ( Oracle is silent ) nobody is using it.

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