Date: Wed, 18 Nov 2009 16:54:28 -0500 From: Steve Bertrand <steve@ibctech.ca> To: Nerius Landys <nlandys@gmail.com> Cc: questions@freebsd.org Subject: Re: Measuring disk I/O Message-ID: <4B046D14.1070505@ibctech.ca> In-Reply-To: <560f92640911181259m37d2659w775fa3fafd9499b6@mail.gmail.com> References: <560f92640911181259m37d2659w775fa3fafd9499b6@mail.gmail.com>
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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
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