Thanks for the clarification, I didn't find it earlier.
Not sure if this may be useful in checking recording status nugget recordings
It would be. It pulls the list of active recordings out of the Humax settop program's memory in eldritch fashion. The
{system busy} class method wraps a call to the
lsof Linux command (eldritch in itself) to list recording files that the Humax settop program has open.
I believe there is also some code that checks for imminent scheduled recordings (the queue system?) which is just a database query. The interface that would allow the system to detect a user's future intention to press the Record button is missing.
Yes, as expected truncating the file to 0 is equivalent from the filesystem perspective to
rm <filename>.
trm is intended to limit resource usage by repeatedly truncating a small portion from the end of a large file until the file has length 0. Possibly it could do that by opening the file,
unlink()ing it (so it appears to be deleted from its directory, and can't easily be accessed by another process), repeatedly
ftruncate()ing the file until the file has 0 length, then closing the file, causing it to be finally removed from the filesystem; this seems to match its external linkages.
The second reference is useful. It confirms what
@MymsMan found with
ionice (ie, no visible effect, albeit a somewhat different test case). Commenters say, plausibly, that the problem is with Ext3 listing every block in use and then unwinding that list (via index blocks, etc). Also, the author had a system described as "very beefy" for 2010, yet had trouble deleting files only a tenth of the size of a typical recording.ts, whereas the BCM7405 with 128MB RAM is very much at the non-beefy end of the scale.
...I just did a stress test, recording from BBC4HD while deleting 21GB from [Recycle Bin] (taking about 7 minutes). There were no disturbances live that I noticed, but there certainly were in the recording.
That sounds like a good argument for always using the Recycle Bin and ensuring that emptying is only done when recordings are neither due nor scheduled.
