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Date:      Thu, 19 Nov 2009 09:30:29 +0000
From:      krad <kraduk@googlemail.com>
To:        Nerius Landys <nlandys@gmail.com>
Cc:        questions@freebsd.org
Subject:   Re: Measuring disk I/O
Message-ID:  <d36406630911190130xeda7c5en2c7044d9ff322eff@mail.gmail.com>
In-Reply-To: <560f92640911181259m37d2659w775fa3fafd9499b6@mail.gmail.com>
References:  <560f92640911181259m37d2659w775fa3fafd9499b6@mail.gmail.com>

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2009/11/18 Nerius Landys <nlandys@gmail.com>

> 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?
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If you are worried about disk io and your db isnt to big, but to big to fit
into ram, get a SD drive and put the db data on it. If your db is to big to
fit on a sensibly priced SD, and your machine is suitably speced you could
look at creating a zfs pool with a SD configured as an l2arc. The SD will
then cache the most accessed parts of the db, and can dramatically increase
performance.

I am assuming that you have optimized your code though as well, as this
should be your 1st point of call



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