On Fri, February 27, 2009 05:50, Baron Schwartz wrote:
> On Fri, Feb 27, 2009 at 4:19 AM, <dbrb2002-sql@stripped> wrote:
>> Hi
>>
>> Recently I noticed the server takes lot of time on and off when opening
>> and closing tables. And I tried to increase the table_cache more the the
>> total tables (file_limit is properly set); and the problem still
>> continues and lowering it also continues.. and tried to set in middle..
>> same
>>
>> Any thoughts on fixing this ? I am going crazy..
>>
>> Sometimes the threads spin 10-60secs in just opening and closing tables
>> state..
>
> Have you checked to see if your disk is saturated with requests? Try
> this:
>
> vmstat 5 5
> iostat -dx 5 5
Slight variant if you use logical volumes.
iostat -x 10 /dev/sda /dev/sdb /dev/sdc /dev/sdd /dev/sde
Where the /dev/...'s are the actual base disks. W/O the -d you get cpu
loads as well. I use top -i (then z for color) if I need to know what
processes are running. The is on Debian GNU Linux.
Look at the await column:
"The average time (in milliseconds) for I/O requests issued to the device
to be served. This includes the time spent by the requests in queue and
the time spent servicing them. "
> Assuming you're on a Unix-like OS.
>
> --
> Baron Schwartz, Director of Consulting, Percona Inc.
> Our Blog: http://www.mysqlperformanceblog.com/
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