Re: Increase in 'log file sync' waits while 'log file parallel write' remains unchanged
Date: Mon, 21 Sep 2009 16:52:33 -0700 (PDT)
Message-ID: <bf1d2925-fb00-485d-937e-e8dc7c5671c3_at_12g2000pri.googlegroups.com>
> Do you have available cpu time on this system when the log file waits
> shoot up?
This is LPAR on big AIX p595 frame, it has 32 CPU.
> Unless you are showing some signs of severe cpu starvation ( that
> might have been missed possibly ) I think you gotta check out the IO
> subsystem.
> My databases get about .5 ms for log file sync ... 10 ms is ugly and
> 100 ms just ouch.
'log file sync' is wait experienced by foreground user process while
'log file parallel write'
is wait event experienced by Log Writer. I thought that slow I/O will
lead to increase
in 'log file parallel write'.
I checked db once agai, found that log_buffer is set to 1MB. If we
unset it the
default value will be 4 MB (128K * cpu_count), I don't think it will
help.
> Local storage or SAN? Can you get some iostat information during the
> bad times?
Yes, this is EMC DMX-something (2000). Received on Mon Sep 21 2009 - 18:52:33 CDT