RE: Reducing downtime for backups

[prumschlag@xxxxxxxxxx]

Chris,

Don't take this wrong, but I have trouble swallowing that.  I have to go back to
basics on this and in my (admittedly simplistic) view it goes like this:  CPU -
Fast;   Disk - Not So Fast,   Tape - Really Slow.  For this job, the CPU has
nothing else to do, so it will always be waiting on the disks, so no matter how
many I throw at it the disk busy percentage will always be high.  If my lousy
memory serves me correctly, IBM invented *SAVF files for the express purpose of
reducing downtime for backups.  Has tape processing improved so much that one
tape drive can record data faster than 6 read/write heads on disk?  Or is it
possible that the RAID processing on these disks is causing so much thrashing
that the whole system is bouncing up and down in the computer room?

Phil


   Message: 9
   From: Chris Bipes <chris.bipes@cross-check.com>
   To: "'midrange-l@midrange.com'" <midrange-l@midrange.com>
   Subject: RE: Reducing downtime for backups
   Date: Fri, 30 Nov 2001 11:51:52 -0800
   Reply-To: midrange-l@midrange.com

   If you have 6 drive in the ASP and they are at 90+%, well that is your
   bottle neck.  More drive will improve performance.  Sound like your IOP is
   ok, NOW.  Adding more drives means more data transferred faster thus more of
   a load on your IOP.  With out know your rack config and processor it would
   be hard to say exactly what to do.  Low CPU and IOP with high DISK
   definitely point to more disk arms in the *SAVF ASP.  What is comes to is
   where you want to spend your money, DASD or TAPE?

   JMHO,

   Christopher K. Bipes     mailto:ChrisB@Cross-Check.com
   Operations & Network Mgr  mailto:Chris_Bipes@Yahoo.com
   CrossCheck, Inc.         http://www.cross-check.com
   6119 State Farm Drive    Phone: 707 586-0551 x 1102
   Rohnert Park CA  94928        Fax: 707 586-1884