[mythtv-users] MySQL on SSD 99% Utilization

Glenn Sommer glemsom at gmail.com
Fri Feb 4 05:51:27 UTC 2011


2011/2/3 Brian Long <briandlong at gmail.com>:
> I've finally gotten my new backend up and running.  It's a Core i5-750 with
> 4GB RAM and 6TB disk.  I'm seeing something strange and I wonder if I should
> have put MySQL on my spinning disk instead of my OS SSD.  I have the OS on a
> Kingston SSD Now 30GB drive (not the best performer, but great for a small
> OS).  I also have /var/lib/mysql on this disk.  With two commflag jobs
> running, my host has a load of 4, CPUs are only running at 1.2GHz and iostat
> shows the SSD is 99% utilized:
>
> Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz
> avgqu-sz   await  svctm  %util
> sdg               0.00    26.00    0.00  129.00     0.00   400.00
> 6.20     0.99    7.61   7.65  98.70
>
> The CPUs are doing almost nothing so it appears the MySQL updates being
> performed during a commflag are screwing with the SSD.  Is it generally a
> bad practice to put MySQL on a SSD?  I figured it would provide a nice fast
> DB and keep my DB separate from my recording disks, but I guess I was wrong.
>
> Thanks for any tips.
>
> /Brian/
>
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There's a HUGE difference on SSD's performance (price and performance
often go and in hand here)
For example the newer Intel X-25 series costs about 3 times as much as
the cheepest SSD models (kingston for example).
But, they are also A LOT faster!

With that said, a cheep SSD can still be a good choice if you don't
need super performance - but just want a quiet, low-power, low-heat
system.

For reference, please take a look here:
http://www.tomshardware.com/charts/ssd-charts-2010/I-O-Performance-4K-Random-Writes,2362.html


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