[mythtv-users] combined myth/server

[Travis Tabbal]

On Wed, Apr 21, 2010 at 8:42 PM, Indulis Bernsteins
<indulis.b at au1.ibm.com>wrote:

>
>
> It really is worth setting up a filesystem to match the workload's
> requirements!  If you try XFS and set it up as I have, I am sure you will
> find it to be very capable at coping with multiple Mythtv recording streams.
>


I did. XFS set per the wiki. The problem is made worse by MythBackend doing
sync calls once a second or so, so the filesystem isn't really able to
optimize write seeks. It's forced to seek once per second per recording,
minimum. Add in DB and general system overhead, and it can use up too much
time. I was able to patch that sync call out and improve the situation
significantly, but I got tired of compiling my own Myth packages and the
multi-drive setup was simpler. It's possible the devs changed this behavior
in a more recent version. There was a big thread not so long ago about this
issue. You could sit and listen to the drive sound like a clock in there
tick-tick-tick once per second.

As mentioned, if it works for you, great. However, a large number of users
have reported problems that were solved by separating the spindles. There is
a good reason that people recommend new users consider this path, it's been
proven to make a difference in real life. It also eliminates the need to
tune filesystem parameters, though that is still recommended. And as this
thread was started regarding combining the Myth backend with general file
server duty, that's only going to make time lost to seeking worse. Again,
workloads and system vary. I'll also note that over time filesystem
fragmentation might come into play as well. Though I never saw significant
fragmentation % numbers with XFS set per the wiki on my recordings
partition.
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