Re: Performance problems

In article <3756CBFE.B27DB9E0@bloomberg.net>, kagel@bloomberg.net wrote: > [ ... snip ... ] > for any busy chunks, with the number of LRUS as a minimum. So if you > increase LRUS to 32 use AIOVPS of 32 otherwise at least 14. Monitor > onstat -g iov at least one or two of the aio VPs should show <1 IO/wkup> indicating that at least some of the time that VP was awakened another > AIO VP had freed up to perform the IO before it was fully awake. If > not you can take advantage of even more AIO VPs. > > Art S. Kagel > Art, I'm a bit confused about this AIO VP business. According to the (7.3) manual: "If your operating system supports KAIO, the CPU VPs make I/O requests directly to the file instead of the operating-system buffers. In this case, con-figure only one AIO VP, plus two additional AIO VPs for every buffered file chunk." I assume Doris' system uses KAIO, since it is supported on AIX, and probably using raw disks. So all I/O work should be done by kaio threads, running on cpu vps. What are the AIO VPs doing? TIA Gabor -- Gabor Heppes IBM Global Services gaborh@au1.ibm.com Sent via Deja.com http://www.deja.com/ Share what you know. Learn what you don't.

> > "If your operating system supports KAIO, the CPU VPs make I/O requests > directly to the file instead of the operating-system buffers. In this > case, con-figure only one AIO VP, plus two additional AIO VPs for every > buffered file chunk." > > I assume Doris' system uses KAIO, since it is supported on AIX, and > probably using raw disks. So all I/O work should be done by kaio > threads, running on cpu vps. > > What are the AIO VPs doing? > In the case, when all chunks are raw devices and KAIO is enabled, AIO VP's responsible for I/O to the log files. You need 1 or AIO VP's in this case. -- With best regards, Yuri Dovgart, SAP R/3, Informix consultant, "Telecominvest" company. E-mail y_dovgart@tci.ukrtel.net Sent via Deja.com http://www.deja.com/ Share what you know. Learn what you don't.