[mythtv-users] Storage group question
Michael T. Dean
mtdean at thirdcontact.com
Mon Jan 14 00:05:50 UTC 2013
On 01/13/2013 06:51 PM, Paul Stillwell wrote:
> If I have a recording rule set up to record to a specific Storage Group (e.g. LiveTV) and the specified storage group fills up, what will happen? Will a scheduled recording be ignored or will a recording be deleted in that storage group and the new recording be put in there? Or something else?
>
When a file system fills up and MythTV chooses to use that file system
(note that this is at a level /beneath/ Storage Groups), it will attempt
to delete an existing recording from that file system while it's
recording the new show. When it deletes a recording, it does so by
using the auto-expiration method you've configured. For all users, the
first shows expired will be not-in-progress Live TV recordings (i.e.
those recordings of already-ended shows or show pieces that were
partially recorded, but have "ended" because the user exited Live TV or
changed channels in Live TV), then Deleted recordings (recordings in the
Deleted recording group), then other recordings for which "Allow
auto-expiration" is enabled. If you have no recordings that allow
expiration (and MythTV has already deleted, or you don't have any, Live
TV or Deleted shows), MythTV will just write data until the kernel stops
it, at which point Bad Things Happen...
So, important points are:
a) Storage Groups are not necessarily related to file systems. You may
have a Storage Group, such as Default, that contains multiple
directories (such as /srv/mythtv/tv/a/recordings and
/srv/mythtv/tv/b/recordings, where /srv/mythtv/tv/a and /srv/mythtv/tv/b
are mount points for 2 separate file systems on 2 separate disks).
b) MythTV will only expire shows from file systems that are in use.
c) MythTV chooses which directory/file system to use based on the
Storage Group Disk Scheduler you've specified (
http://www.mythtv.org/wiki/Storage_Groups#Storage_Group_Disk_Scheduler ).
So, If the file system at /srv/mythtv/tv/b is full, and MythTV is told
to write to the Default Storage Group, but chooses to use
/srv/mythtv/tv/a/recordings, then no recordings will be expired.
However, if another recording starts and MythTV chooses to use
/srv/mythtv/tv/b/recordings (the full file system), it will need to
expire Live TV or Deleted recordings or other recordings to make room
for the new recording.
Also, if you have any full file systems--i.e. if you plan to let
auto-expiration remove files, you almost definitely should not use the
Balanced Free Space Storage Group Scheduler. You'd be better off with
the Balanced Disk I/O or the Combination Storage Group Disk Scheduler.
Mike
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