Yes, there is overhead on tape, but the tape drives will theoretically write at rated write speed TIMES THE COMPRESSION RATIO. I have seen a sustained 60 MB/second into a 3590 tape drive. It required high powered hardware and significant tuning to get this rate.
Such high performance is only attainable if the processor, disk, ethernet, or ?? will also sustain this rate. Performance is limited by the slowest component. Your parity of performance between disk and tape storage pools does not surprise me. Something other than the disk or tape is constraining your system. The rate you are seeing will give the first hint as to that bottleneck. Orville L. Lantto Datatrend Technologies, Inc. (http://www.datatrend.com) IBM Premier Business Partner 121 Cheshire Lane, Suite 700 Minnetonka, MN 55305 Email: [EMAIL PROTECTED] "Pearson, Dave" <[EMAIL PROTECTED]> Sent by: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]> 07/24/02 01:31 PM Please respond to "ADSM: Dist Stor Manager" To: [EMAIL PROTECTED] cc: Subject: Re: diskpool performance ON Tape... It take time to unwind, take the tape out, put another tape in then start processing... With Diskpool. Thre is non of this. My thought Dave Pearson > -----Original Message----- > From: Orville Lantto [SMTP:[EMAIL PROTECTED]] > Sent: Wednesday, July 24, 2002 11:03 AM > To: [EMAIL PROTECTED] > Subject: Re: diskpool performance > > What are your throughput values? Tape is not necessarily slower than > disk, especially when the data is compressed on the tape drive. > > Orville L. Lantto > Datatrend Technologies, Inc. (http://www.datatrend.com) > IBM Premier Business Partner > 121 Cheshire Lane, Suite 700 > Minnetonka, MN 55305 > Email: [EMAIL PROTECTED] > > > > > > Steve Freeman <[EMAIL PROTECTED]> > Sent by: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]> > 07/24/02 11:00 AM > Please respond to "ADSM: Dist Stor Manager" > > > To: [EMAIL PROTECTED] > cc: > Subject: diskpool performance > > > Please could someone advise me on the following issue we have with tsm. > I am a TSM novice and would appreciate some pointers etc. > > Environment : TSM 4.2.0 AIX4.3.3 ML09 Server and Client on same Server > using Sharedmem > > 2 Stgpools defined diskpool and tapepool > > we have created a diskpool on RAID5 and created random access volumes > Total Diskpool size is 150GB. Our nextpool is tapepool for migration > upon high thresholds being reached. > > We have compression turned off on the client and set the selftune > parameters in dsmserv.sys > SELFTUNEBUF > SELFTUNETXN > > > Issue: IF we initiate a client backup using sharedmem to the diskpool, > it seems to take the same time as it does to backup the client straight > to tapepool. I would have thought the diskpool access > would be quicker ? > > The Diskpool is located on direct fibre attached storage with large > read/write cache. The tapepool > is SCSI attached ATL library with 2 drives > > Any suggestions or pointers to increase the throughput to a respectable > level would be appreciated. > > kind regards > steve freeman > [EMAIL PROTECTED]
