[mythtv-users] remove deleted recording to make bandwidth?

Chris Pinkham cpinkham at bc2va.org
Wed Jun 2 16:42:46 UTC 2010

* On Wed Jun 02, 2010 at 09:24:58AM -0400, Brian J. Murrell wrote:
> If I have a storage group with three disks in it and my BE wants to
> record three simultaneous programs, it should record one program to each
> spindle.  This is indeed a wonderful feature.

This sounds like you're using either the balanced I/O setting or the
original (was the default but not now) setting which takes into account
I/O, free space, and local vs remote.

> However, if one of the disks is full but has recordings marked for
> deletion, will one of those marked-for-deletion recordings be purged to
> allow the 3 simultaneous recordings each to have their own spindle?
> If so, is this purging done prior to the recording starting or is it
> done as the new program is being written to the full disk?

The recording scheduler will not auto expire any recordings to make room
for new ones, the scheduling code and the auto expire code do not talk
to this extent.  What will happen depends on what storage group
scheduler you're using.

If you're using the 'balanced I/O' or combination/original method,
then Myth will attempt to spread the load out using filesystems with
enough disk space.  If there are none that have enough disk space, the
code will punt and put the recording on the first disk in the sorted
list (ie, the one with the least I/O or most free space if there are
multiples with the same I/O but differing amounts of free space).

If you're using the 'balance free space' setting, then Myth will try to
put a new recording on the disk with the most free space.  If there
is not a disk with enough free space, the scheduler will then go through 
a simulation process to see where the new recording would fit if old files
were expired in order.  If no filesystem has enough space, then the
scheduler will try to put the new recording on the filesystem with the
most free space.  Hopefully you don't get to that point since that would
mean you don't have anything that can be expired to make space for the
new recording.

I never let my drives fill up, although I do have recordings set to
auto-expire, they usually get watched before that happens.  So, I use
the original/combination method which balances out I/O across the five
drives in my Default Storage Group.


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