[mythtv] Re: New idea for storing recordings to disks

danielk at cuymedia.net danielk at cuymedia.net
Wed Jun 29 17:25:30 UTC 2005

On Wed, 29 Jun 2005 10:58 , 'Joseph A. Caputo' <jcaputo1 at comcast.net> sent:
>(1) if your auto-expire space threshold  is not at least as large as 
>the max number of bytes a recording could consume in , you could 
>still run out of space (not too likely, but possible)
>(2) if auto-expire runs, but there's nothing that can be expired, you're 

>Bottom line is still, to *guarantee* you won't run out of space 
>mid-recording, you must set the new recording space threshold high 
>enough, figuring in factors like multiple tuners and transcoding jobs 
>that may also consume space.

Actually, the code in SVN guarantees that you won't run out of space if
 1/ There are sufficient recordings to autoexpire AND
 2/ Any shared disk is shared with the master backend AND
 3/ Any non-myth application's disk usage is accounted for in the
   'extra space' disk space reservation on each backend.
 4/ There are no problems with deleting the files. This might happen
    if you are watching a program that MythTV wants to autoexpire.

So (1) is mostly taken care of, (2) should be solved with a warning to
the user and a graceful abort of any ongoing recordings.

Solving (1) for multiple disks won't be a 1 day project, but it isn't
rocket science. You can estimate the amount of space a recording will
take with GetMaxBitrate() and the length of the recording. Then you
just have to determine what needs to be deleted on each disk to fit
the next recording (don't pre-delete it however), and then pick the
least objectionable one. You can then have use the existing AutoExpire
functionality, simply create one for each disk on each backend.

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