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From:Kevin Burton Date:May 6 2005 8:58pm
Subject:MySQL not using optimum disk throughput.
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We have a few of DBs which aren't using disk IO to optimum capacity.

They're running at a load of 1.5 or so with a high workload of pending 
queries.

When I do iostat I'm not noticing much IO :

Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s 
avgrq-sz avgqu-sz   await  svctm  %util
sda          0.00  13.73 128.43 252.94 1027.45 1695.10   513.73   
847.55     7.14    90.13  285.00   2.53  96.57

...

This is only seeing about 500k -> 1M per second throughput.

When I run bonnie++ on these drives they're showing 20M->40M throughput.

Which is really strange.

Most of our queries are single INSERTS/DELETES.  I could probably 
rewrite these
to become batch operations but I think I'd still end up seeing the above 
iostat
results but with higher throughput.

... so I'd like to get to the bottom of this before moving forward?

I ran OPTIMIZE TABLE on all tables but nothing. 

The boxes aren't paging.

They're running on a RAID5 disk on XFS.

Could it be that the disks are having to do a number of HEAD seeks since we
have large tables?

-- 


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Thread
MySQL not using optimum disk throughput.Kevin Burton6 May
  • Re: MySQL not using optimum disk throughput.Dan Nelson7 May
RE: MySQL not using optimum disk throughput.Dathan Pattishall7 May
  • Re: MySQL not using optimum disk throughput.Greg Whalin7 May
    • Re: MySQL not using optimum disk throughput.Kevin Burton7 May
      • Re: MySQL not using optimum disk throughput.Greg Whalin7 May
        • Re: MySQL not using optimum disk throughput.Kevin Burton7 May
          • Re: MySQL not using optimum disk throughput.Kevin Burton7 May
            • Re: MySQL not using optimum disk throughput.Greg Whalin7 May
              • Re: MySQL not using optimum disk throughput.Kevin Burton7 May
                • Re: MySQL not using optimum disk throughput.Atle Veka7 May
                  • Re: MySQL not using optimum disk throughput.Kevin Burton7 May
                    • Re: MySQL not using optimum disk throughput.Atle Veka7 May
                  • Re: MySQL not using optimum disk throughput.Dan Nelson8 May
              • Re: MySQL not using optimum disk throughput.Peter Zaitsev7 May
                • Re: MySQL not using optimum disk throughput.Greg Whalin7 May
                  • Re: MySQL not using optimum disk throughput.Peter Zaitsev1 Jun
                    • RE: MySQL not using optimum disk throughput.Richard Dale1 Jun
        • Re: MySQL not using optimum disk throughput.Kevin Burton9 May
          • Re: MySQL not using optimum disk throughput.Greg Whalin9 May
            • Re: MySQL not using optimum disk throughput.Kevin Burton9 May
              • Re: MySQL not using optimum disk throughput.Greg Whalin9 May
                • Re: MySQL not using optimum disk throughput.Kevin Burton9 May
Re: MySQL not using optimum disk throughput.John David Duncan7 May
  • Re: MySQL not using optimum disk throughput.Peter Zaitsev7 May