Originally posted by: vbaranov
"maxpout/minpout" watermarks are so-called "Disk-I/O pacing", which is intended to prevent programs that generate very large amounts of output from saturating the system's I/O facilities and causing the response times of less-demanding programs to deteriorate. Neither IBM doc does mention it affects paging, nor I think it is a case in your case.
If "paging space I/Os blocked with no psbuf" increased rapidly over the time in "vmstat -v" output, you should increase "numfsbufs" using "ioo". Read the detailed explanation at
http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?topic=/com.ibm.aix.prftungd/doc/prftungd/disk_io_pacing.htm (remove space(s) in the link above if any appears in the message' body).
This document contains almost everything you may need regarding the performance tuning.
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