Lars Bebensee wrote: >Hi guys, > >this is actually not a TSM question but one for the hardware gurus. We are >running a backup under AIX using the savevg command and Ultrium 3580 tape >drives. With topas I can see a data transfer rate of about 1MB/sec. We >attached the drives via Fibre Channel and a SAN Data Gateway. The blocksize >of the drive was set to 2048 (since one of the SAN guys told me FC >transfers with a blocksize of 2048). I started savevg with "-b4" meaning to >write 4x512Byte blocks (=2048). With the mentioned speed the drives are >seriously crawling. Am I missing out something here? Any clues?? > >Thanks > >Lars > > Hi,
I think your problem is you are not feeding the data to the tape drive fast enough for it to stream, therefore it is stopping waiting for data and then starts when it gets some. The stop and starts kill the performance. I would try increasing two different values: chdev -l sys0 -a maxbuf=100 savevg -b200 ............. This should improve the streaming of data to the tape drive. You may have to play with these numbers some to get the optimal performance. Good Luck and let us know how you did. -- Regards, Mark D. Rodriguez President MDR Consulting, Inc. =============================================================================== MDR Consulting The very best in Technical Training and Consulting. IBM Advanced Business Partner SAIR Linux and GNU Authorized Center for Education IBM Certified Advanced Technical Expert, CATE AIX Support and Performance Tuning, RS6000 SP, TSM/ADSM and Linux Red Hat Certified Engineer, RHCE ===============================================================================
