On Wed, Nov 18, 2009 at 3:54 PM, Steve Bertrand <st...@ibctech.ca> wrote:

> Nerius Landys wrote:
> > A friend and I are working on a small video-game related project as a
> > hobby.  We're running several scripts 24/7 that make lots of calls to
> > a MySQL database.  The mysql server process shows an average CPU use
> > of 1% (reported by top) and it never goes above about 2%  The tables
> > it's hitting are myisam tables.  I'm a little bit worried that the
> > mysql process is using a lot of disk access.  I don't know too much
> > about hard disks but my feeling is that too much disk use could slow
> > the machine down or cause a premature hard disk failure.  WD Raptor
> > model.
> >
> > I don't know if my concerns are well-founded, but I would like to
> > measure impact on the hard disk somehow.  I don't know how to see disk
> > I/O.  I do know how to use top.  How do I measure disk I/O?  Any other
> > thoughts?
>
> Perhaps gstat(8) will help you get started:
>
> # gstat -a
>
> dT: 1.001s  w: 1.000s
>  L(q)  ops/s    r/s   kBps   ms/r    w/s   kBps   ms/w   %busy Name
>    4    176    114  10261   14.9     62    607   25.4   96.8| ar0
>    4    177    115  10389   17.8     62    607   26.5  100.0| ar0.eli
>    1     34     34    527   30.8      0      0    0.0   99.1| ar0.elie
>    2     66      4     16   20.5     62    607   26.6   98.0| ar0.elif
>    1     77     77   9845   12.1      0      0    0.0   93.0| ar0.elig
>
> ...or on ZFS:
>
> # zpool iostat 1
>
>               capacity     operations    bandwidth
> pool         used  avail   read  write   read  write
> ----------  -----  -----  -----  -----  -----  -----
> storage     1.39T   440G      0    771      0  96.4M
> storage     1.39T   440G      0  1.05K  4.42K   126M
>
> Steve
>
>
systat -io is a nice visualization.

If you're really io bound there are some things you can do config wise to
help.  However if you really are pushing a lot data, you need to be running
scsi or ssd drives.  It takes A LOT of striped sata drives to match the
performance of a single good 15K scsi.  if you're able to run ahci, that
will help some as well.

-- 
Adam Vande More
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