[mythtv-users] When does MythTV check minimum free space?

[Peter Watkins]

When does MythTV check the free space in storage directories? (FWIW
I'm running Ubuntu's MythTV 0.23+fixes on Ubuntu 10.04 LTS.)

I'm working on my script to re-balance expirable recordings in storage
groups that have multiple storage directories
(http://www.mythtv.org/pipermail/mythtv-users/2011-January/307647.html).
It would be very handy if I could just move files from one directory
to another, and I do have the minimum free space set high enough that
there's virtually always enough room -- but only if MythTV doesn't see
the short term decrease in free space and decide to autoexpire
something right away.

Example:
/disk1/recordings -- 1000 GB partition, 30 GB minimum free, normally
about 32 GB free
/disk2/recordings -- 1500 GB partition, 30 GB minimum free, normally
about 32 GB free

My script wants to swap /disk1/recordings/program1.mpg and
/disk2/recordings/program2.mpg. Let's say each recording uses 7 GB.

The end result will be the same -- 32 GB free on each disk. But while
each recording is being copied/moved, the target directory will dip
down to about 25 GB free. My script is smart enough to at least avoid
scheduled recordings -- is that good enough? Does MythTV just check
the free space if there are fewer than N minutes before the next
scheduled recording (or when someone uses Live TV)? Or does the
backend(?) check every M minutes regardless of encoder status and
recording schedule?

I know I can use an additional directory that doesn't reside on the
same partition as a storage directory to ensure that even LiveTV use
won't cause problems (program1 from disk1 to extra dir, program2 from
disk2 to disk1, program1 from extra dir to disk2), but that seems
clunky, especially when each copy operation (for the main recording
video file) will often take one or two minutes.

Thanks,

Peter