[mythtv-users] autoexpire hell

[James Linder]

> On Feb 4, 2025, at 17:13, Stephen Worthington <stephen_agent at jsw.gen.nz> wrote:
> 
> On Tue, 4 Feb 2025 14:24:27 +0800, you wrote:
> 
>>> On Feb 4, 2025, at 11:32, jam <jam at tigger.ws> wrote:
>>> 
>>> There is a long story involving dual usb tuners ...
>>> 
>>> I've setup another master backend with /store as the main directory
>>> 
>>> I'm restoring files and backups to rationalize everything.
>>> 
>>> My 4T /store is now 96% full (flash so the usual rules don't apply: keep your usage under (say) 80%)
>>> 
>>> I deleted junk-recordings to make space, but how do I force autoexpire to run?
>> 
>> Peter I would be incredibly useful to have a button [ ] autoexpire now on webbackend.
>> I peruse the API which IMHO is seriously deficiant:
>> I would let to see
>> GetFileList be able return the list of “deleted” group files, and a
>> AutoExpire fileName.
>> 
>> If anybody can correct me, please do.
>> I shall write a Qt file deletion app that may be of interest to Peter, or others. Concerted learning ahead
> 
>> James
> 
> Autoexpire normally happens when you run out of space on a recording
> partition and mythbackend wants to record to it.  It also happens
> regularly, but I am not sure how often.  Try:
> 
> grep -i autoexpire /var/log/mythtv/mythbackend.log
> 
> The amount of free space that autoexpire will create on each recording
> partition seems to default to about 20 Gbytes.  I have never found the
> exact number, but if I keep the free space above that, I do not get
> any autoexpiring of recordings happening.  There may well be settings
> for these things, but I have never found them.  To get mythbackend to
> autoexpire down to 80% of 4 Tbytes, you would need to set the
> autoexpire size to 240 Gbytes on that partition only (you would only
> want 20 Gbytes on hard disk partitions).
> 
> The normal way to ensure that your flash has enough spare blocks so
> that it can erase them in time for reuse is to only format 80% or 90%
> of the flash drive into partitions accessible by the system.  This is
> called "overprovisioning".  The remaining unparitioned space then
> provides that many flash blocks that the flash's operating system can
> use for its erased block queue, even when the rest of the flash is
> full.  Since flashes assign the address of each block as required,
> blocks in unformatted space are not left unused as they are on a hard
> drive.  The flash operating system uses all of the blocks on the drive
> and just changes the address as they go on and off the erased list.
> 
> See:
> 
> https://www.techtarget.com/searchstorage/definition/overprovisioning-SSD-overprovisioning
> 
> So you should not need to use the MythTV autoexpire to provide any
> free blocks to keep the flash drive running at full speed.  The free
> blocks should be provided via overprovisioning.


Stephen thanks. The trouble is me doing not-normal stuff.

You may recall, you did offer a reply, I had an issue with usb-tuners. I complately setup a new system and got all working.
I recovered all Videos plus meta data by copying all video* tables in the DB.

To recover any recordings I setup an alternative-master backend. BUT it has no tuners, so autoexpire does not happen.

What does work, but is somewhat tedious

Delete unwanted recordings
Change group filter to DELETED

Delete the entries.

They are finally gone.
I want to automate for me and there have been (many silly) requests to do so that so I shall

RESTORING A BACKUP RESULTS IN DAMAGED RECORDINGS (marked as such, and pixelated) Some time spent trying to resolve, without success.

James