[mythtv-users] Mythbackend recording glitches

Stephen Worthington stephen_agent at jsw.gen.nz
Thu Oct 18 01:53:19 UTC 2018


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.


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