[mythtv-users] Mythbackend recording glitches

[Allen Edwards]

On Wed, Oct 17, 2018 at 8:03 PM Allen Edwards <allen.p.edwards at gmail.com>
wrote:

>
>
> On Wed, Oct 17, 2018 at 6:53 PM Stephen Worthington <
> stephen_agent at jsw.gen.nz> wrote:
>
>> On Wed, 17 Oct 2018 12:08:18 -0700, you wrote:
>>
>> >That is the one.  I might have made a mistake using the i386 version.  I
>> >had a reason but I am not sure it was a valid reason. At the time, I did
>> >not know for sure that the failure was just the disk and not the MB so I
>> >was thinking I might have to get a new system and that I would get Intel.
>> >I thought I might be able to use the same HD and install but that very
>> well
>> >might be wrong.
>> >
>> >I do wonder if that processor and MB are able to run Ubuntu 16 without
>> >issues. The processor load does not look like it should be causing
>> >problems.  The only thing that takes a lot of processor is mythcommflag
>> and
>> >disabling that doesn't help the problem.
>> >
>> >Allen
>>
>> That processor should be fine.  It may not be able to do mythcommflag
>> in real time, but it certainly will be able to record properly.  My
>> mother's MythTV box is running Mythbuntu 16.04 on an ancient AMD
>> Athlon II X2 245 2.9 GHz dual core processor and that is fine.  What
>> may not be fine is that MythTV uses rather more RAM now.  My mother's
>> box only has 4 Gibytes of RAM, and while that does work, it swaps when
>> she needs to use Thunderbird or Firefox.  Having less than 4 Gibytes
>> of RAM might be a problem.
>>
>> But you really do need to change to using the 64-bit version.  As of
>> 18.04, Ubuntu no longer supports the i386 version, and for a number of
>> versions before that the support has not been good - the i386 versions
>> tend to have problems.  And MythTV has not been tested much on i386
>> versions for a long time.
>>
>> To change to a 64-bit version, this should work:
>>
>> 1) Install gparted.  Use it to shrink down your EXT4 partition so you
>> have enough room to create a new partition to hold your existing
>> recordings (and anything else you want to save).
>>
>> 2) Create a JFS or XFS partition in the spare space.  To use JFS, you
>> may need to install the jfsutils package.  Add it to fstab and mount
>> it.  I call my recording partitions "rec1", "rec2", and give them
>> labels so that I can use the LABEL= format in fstab.  I find that much
>> saner to use than UUIDs.  I mount the partitions under /mnt, using the
>> same name for the mountpoint as the partition label:
>>
>> /mnt/rec1
>>
>> Make sure the mount point is accessible to MythTV.
>>
>> 3) Create a subdirectory for storing your recordings on the new
>> partition.  I use "recordings".  Make sure the subdirectory is
>> accessible to MythTV (making it mythtv group should do that, but I
>> just make mine universally accessible).
>>
>> 4) Use mythtv-setup to add the new subdirectory (eg
>> /mnt/rec1/recordings) to the Default storagegroup.
>>
>> 5) Move all the recording files to the new partition:
>>
>> mv -v /var/lib/mythtv/recordings /mnt/rec1/recordings
>>
>> 6) Run mythfrontend and check that the recordings are still accessible
>> from there.
>>
>> 7) Copy anything else you want to save from the existing system
>> partition across to the new partition.
>>
>> 8) Shut down mythbackend and then use
>> /usr/share/mythtv/mythconverg_backup.pl to create a database backup on
>> the new partition.
>>
>> 9) At this point your system partition should be quite empty and you
>> might like to use clonezilla to do an image backup of it to the new
>> partition (or somewhere else - clonezilla can back up things over your
>> network to other boxes).  I would think the backup would likely be
>> only 10 Gibytes or so, if you use bzip compression.
>>
>> 10) Boot from your 64-bit Mythbuntu install media and tell it to
>> install over the top of the existing EXT4 system partition, rather
>> than using the default option to format and use the whole disk.  You
>> might want to tell it to use only a small size for the system
>> partition, say 50 or 100 Gibytes.  That will leave a gap between the
>> system partition and the new recordings partition.  You can later use
>> gparted to move the bottom end of the recordings partition down so
>> that the extra space is added to it.
>>
>> 11) Reboot into your new 64-bit Mythbuntu.  Do a full "apt update" and
>> "apt upgrade".  Reboot.
>>
>> 12) Add the MythTV PPA and update to the latest version of MythTV that
>> is available.
>>
>> 13) Copy back everything you stored on the other partition.
>>
>> 14) Shut down mythbackend.  Use
>> /usr/share/mythtv/mythconverg_restore.pl to restore your backup
>> database.  Run mythtv-setup, so that the database schema will update
>> if it is different from the backed up version.  Exit mythtv-setup and
>> start mythbackend.
>>
>> 15) Start mythfrontend and check that it is working and can see the
>> old recordings.
>> _______________________________________________
>>
>
> OK, well I have 2G of memory.  That might be a problem then.  I ordered a
> new 1T HD and was going to put the new system on there from scratch. One
> issue is that the 750G drive I am using is old as well so I was thinking a
> new one might be a good idea.  Not sure what I was going to do with the old
> recordings... The main goal is to get a system that works.
>
> Allen
>

New information. Watched a show recorded while another show was also being
recorded.  The glitching was terrible.  Must have been 10 times worse.
Given we could record 4 shows with the Mythbuntu-8 I think this is
significant. It is possible I used the 64bit version when I ran 8 so that
is something I can check.  More memory is very inexpensive so I can add
more if needed.  But upgrading to the 64 bit version seems like an
important next step.

Allen
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