[mythtv-users] Performance issues of keeping DB and recordings on different hard drives (was: Better listings for Schedules Direct users. Free!)

[Travis Tabbal]

On Wed, Sep 1, 2010 at 10:08 AM, Gabe Rubin <gaberubin at gmail.com> wrote:

>
> My question is, will I see a performance gain by doing this or is
> there a bigger performance gain by having the system and the database
> on SATA?
>
>

It's not really the interface that matters, it's more about the newer drives
being faster. The performance gain mentioned here is that the database needs
a lot of random I/O, which means seek time. The recordings also need to seek
the drive, so you get a lot of seeking built up which kills performance.
Splitting this up means that each drive only has to seek for one workload.
As long as we have rotating media, this is an issue. So yes, even an older
PATA drive for the OS/DB will boost overall performance of a Myth system.
The biggest difference will be seen while recording or commflagging, but if
you have something going on while mythfilldatabase runs, for example, it
will slow things down. I got a boost on my old system with a 5400RPM 40GB
PATA drive from an old TiVo for the OS/DB, just to give an example. :)



> Second question, if there is a performance gain, what is the best way
> to transfer all the bits over to the older PATA drive without having
> to reinstall everything?  I imagine I need to reformat the PATA and
> partition it similar to how the SATA drive, but don't know much more
> about doing this type of work on linux.
>


Match up the partition layout for any OS and DB mounts. Just make a
directory to mount your recordings drive to and update /etc/fstab to match
up. Copy everything over, then install your bootloader with some overide to
make it install on the other drive. I don't remember the command I used, but
I think I did it while booted to Grub's prompt. :) I believe grub will also
let you tell it to boot from another disk and such.

Then just swap the boot order and you should be good to go. Not sure if it's
any easier then re-installing and restoring a database backup, so pick your
poison.
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