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

Andre mythtv-list at dinkum.org.uk
Wed Sep 1 17:51:56 UTC 2010


On 1 Sep 2010, at 17:08, Gabe Rubin wrote:

> On Tue, Aug 31, 2010 at 11:16 PM, Michael T. Dean
> <mtdean at thirdcontact.com> wrote:
>> As far as the DB optimizations go, I'll leave it to others to help.  The one
>> thing I will say, however, is that having the database's binary data files
>> on the same file system that you're using to record could have a huge impact
>> on performance.  In truth, the best setup puts the database on a separate
>> spindle.
> 
> I see this a lot on the list to now understand that this is pretty
> much the way to do.  However, I do have some questions about
> performance benefits for my particular system.  I just built a new
> system that uses a SATA drive.  My old system used a PATA drive and I
> understand there is a performance gain from switching over to SATA.  I
> would be interested in taking one of my old PATA drives and converting
> using that for everything and just leaving the SATA drive for storage
> of my recordings and possibly to backup the PATA drive (my SATA drvie
> is 2TB, so it makes no sense to not use that to store recordings).
> 
> 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?

I've even seen a problem on a slave backend (with local sata storage) although there is no database, that's on the master backend I found writing the logs can cause glitches in a HD recording! I had two sata disks, one was system and recordings the other recordings only, recordings made to the shared disk were often glitchy especially when the backend started logging h264 errors at a high rate, recordings on the dedicated drive were fine.

The disk was very noisy when seeking between logs and recording, if I was home I knew when I was going to get a bad recording.

Now the slave boots from a usb drive, records to nfs and network logs to the master server, very quiet, even the cpu and graphics fan are quieter without the disks present.

Andre



> 
> 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.
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