[mythtv-users] 30 minute freezups

Greg Woods greg at gregandeva.net
Fri Dec 19 16:14:51 UTC 2008

Every 30 minutes, my system freezes hard for a couple of seconds. This
results in a few seconds lost of every recording every half hour, and a
few seconds pause in any recording I am watching.

I know the underlying cause of this is the fact that I am using "hdparm"
to spin down my disks when not in use. I get the same effect when I
click "Watch Recordings" after the system has been idle for a while.
There will be a freezeup then too, and the disk access light is solid on
for the duration of the freezup (as opposed to rapid blinking that
occurs during disk I/O).

What I want to discover is what is happening every 30 minutes, and is
there any way I can stop it or anticipate it and manually spin the
drive(s) up.

My system is configured such that the OS and the database are on one
drive, and the recordings are stored on two separate drives. That may or
may not be important.

What I do know is, it's not a cron job. I know this because, if the
system is rebooted (and all daemons restarted), the point on the clock
dial where the freezups happen will change. But it is regular every 30
minutes and will continue at the same point on the clock dial until the
next restart.

I suspect it's something that mythbackend is doing; does anyone know if
there is something that mythbackend does every 30 minutes that might
spin up a drive that wouldn't be otherwise accessed?

I know I could stop this by just not spinning down the drives when idle,
but that would greatly increase the power consumption and I'd like to
avoid that solution if possible. Unfortunately the freezeups are causing
the WAF to go down, so simply living with it isn't an option.

Thanks for any thoughts,

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