[mythtv-users] Storage group question

[Paul Stillwell]

On Jan 13, 2013, at 4:05 PM, Michael T. Dean wrote:

> 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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OK, that's what I thought would happen. A related question: Can the same directory be mapped into multiple Storage groups? For example, if I have 3 directories for recordings like this:

/srv/mythtv/a/recordings
/srv/mythtv/b/recordings
/srv/mythtv/c/recordings

Mapped to the following Storage Groups like this:

Default: /srv/mythtv/a/recordings, /srv/mythtv/b/recordings
Sports: /srv/mythtv/c/recordings, /srv/mythtv/a/recordings

Will that be ok? I'm trying to come up with a scheme such that the small space I have on /srv/mythtv/c/recordings that I want to use when I record sports will be safe if I accidentally fill that drive up and some other sports show is going to record.

Paul