[mythtv] mythth 32

[James]

Since I asked for opinion I'd not be so rude as to refute any, but some comments <smile>

> On 9 Jul 2022, at 8:00 pm, mythtv-dev-request at mythtv.org wrote:
> 
> This is not a troll but a genuine question/observation.
> 
> I am biased, I do not like ubuntu because of the endless 'You shall not ... " eg dmesg eg mythtv password.
> 
> After some fumbling I installed 22.04, built from scratch, using anisible, (32-fixes uptodate). I have issues ie playing while recording ... glitch back to beginning ... later ... pause of 15 secs ...
> 
> I installed opensuse leap 15.4: much better but still ocassional (once-a-week) ... pause cica 15 secs ...
> 
> Using the same hardware with fixes-31I've never had any glitches, ever.
> 
> So it seems ubuntu 22.04 is a tad flakey (there were other minor gotchas) and it seems 32-fixes is less robust than 31-fixes.
> 
> This machine runs my development VMs so it is a 4 core i7 NUC with 24G RAM and 8T flash. The only spinning rust is for backups.
> 
> I do not think io is an issue
> /dev/nvme0n1p5:
> Timing cached reads: 37824 MB in 2.00 seconds = 18942.04 MB/sec
> Timing buffered disk reads: 7850 MB in 3.00 seconds = 2616.18 MB/sec
> (I know to take hdparn with a pinch)
> 
> Can anybody comment on 22.04
> Can anybody comment on 32 vs 31
> 

> Ubuntu versions are often a little flakey when they first come out.
> That is one reason why the LTS upgrades are not recommended until the
> .1 version has been released, and you have to manually override the
> system to do an LTS upgrade to a .0 version.
> 
> When running any system in a VM, unless you have one that is fully set
> up for real-time operation, there can be times when the main system is
> busy and delays the operation of the VM. It should not be enough to
> cause problems with recordings though. A 15 second pause is way
> bigger than should ever happen.

My frontend is on the main system, not a vm.

> Ubuntu packages can also have customisations of the code for things
> that Ubuntu does a bit differently. So when you compile from the
> original source without the custom patches, you will not be getting
> that code. It is better to just install the Ubuntu packages from the
> Mythbuntu v32-fixes repository. But again, that should not cause 15
> second pauses.

I was unaware - thanks.

> I have been running v32-fixes for quite a while now, and have not
> found it to be any less (or more) reliable than v31-fixes.
> 
> The timings you posted for I/O are for reads. NVME disks are
> extremely fast always for reads. Where they can be much slower is for
> writes. That will happen (as on any flash memory) if they run out of
> erased blocks and have to erase one before they can write. Recording
> TV to an SSD causes large numbers of SSD blocks to be written to, so
> it is possible that you are running out of blocks on the erased list.
> Do you have the SSDs set up to do TRIM only, or have you set them to
> use the discard option in fstab? If you are doing TRIM only, then
> that is likely only happening once a day at the most (unless you have
> changed that), so no blocks will be being erased until TRIM is run.
> Set the discard option to make the system hand back erasable blocks as
> soon as they no longer form part of a file, so that the SSD can erase
> them immediately.

If there are Ts available for writing, surely 'available' is moot?

> And be aware that by recording to your SSDs, you will be seriously
> increasing the wear on them. Run smartctl on them and check the wear
> values reported by SMART.

According to SMART, based on 2 years of use (hours : 19221) and TBW (Data Units Written:                 37,386,769 [19.1 TB]) them disks will outlast moi.

> When you are playing while recording, is that playing the same
> recording that is currently recording

yup

> , or another different recording?
> The former can be a bit glitchy if you get too close to the point
> where the recording is happening. It is best to stay a few seconds
> back from that point. The code does make an allowance for this
> problem and prevents you from getting what it thinks is too close to
> the point of recording, but the devs who wrote that code seem to all
> be using ATSC, and I think DVB-T is just enough different that you
> need to be a bit further back to avoid problems.

I'll check next time.

Devil-n-Dark Blue Sea: If you have new ie intel-gen 11 hw then you need new os to support it. I must try HSE.
I don't like ubuntu, but they do have a lot of 'nices'.
James
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