[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


More information about the mythtv-users mailing list