[mythtv-users] Source of my IOBOUND problem?

Blammo blammo.doh at gmail.com
Fri Jun 8 00:10:29 UTC 2007

On 6/6/07, Craig Huff <huffcs at yahoo.com> wrote:
> I had been under the impression (apparently wrong) that three (3) SD recording streams
> would not approach the available bandwidth of a standard (reasonably current) PATA disk.
> Did I choose a clunker drive?
> How do you tell (from all that data) that this is the problem (not to argue, but for education)?

Couple other things you might check:

IO Scheduler: I've had really good luck with the "deadline" scheduler,
when it comes to real time applications and heavy disk usage.
Commercial flaggers can pound your disk IO, and the deadline scheduler
seems to make them all play in nice(r) time slices

Thrashing: Consider moving MySQL to a different physical disk.
Especially during things like commercial flagging, the writes can be
rapid and frequent.

Disk Performance: Your HD may be rated for 100M a second, but that's
sequential reads on the best part of the disk. Throwing in 2,3 or 4
more reads/writes to different parts of the disk does way more than
half or quarter that number. Consider additional disks, or some form
of raid/striping.

Commercial Flagging: Consider restricting the time you flag to times
you don't record.. IE midnight to 6am or something.

the problem you're experiecing is fixable, we've all been there at one
phase or another in our myth growth..

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