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From:Dathan Pattishall Date:May 6 2005 10:07pm
Subject:RE: MySQL not using optimum disk throughput.
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What kernel are you running.

If your running 2.6.x use the deadline scheduler or downgrade to
2.4.23aavm 2.6.[0-9] has major problems with the IO scheduler since the
process scheduler is very fast now.


DVP
----
Dathan Vance Pattishall     http://www.friendster.com

 

> -----Original Message-----
> From: Kevin Burton [mailto:burton@stripped] 
> Sent: Friday, May 06, 2005 1:58 PM
> To: mysql@stripped
> Subject: MySQL not using optimum disk throughput.
> 
> 
> 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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> 
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> 
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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