[mythtv-users] Mythbuntu 8.04, LVM, pcHDTV-5500 (V4L) == Hang.

[Roger Heflin]

Francis Hartojo wrote:
> On Fri, Jul 25, 2008 at 2:22 PM, Roger Heflin <rogerheflin at gmail.com> wrote:
>> Were they XFS before you converted to LVM?
> 
> No.  Previously, my partitions were:
> 
> /boot on sda1 (ext3)
> / on sda3 (ext3)
> /u01 on sda4 (xfs)
> /u02 on sdb1 (xfs)
> 
> /u01 and /u02 were where I configured MythTV to store recordings,
> videos, music, etc.
> 
>> I have (on a much older enterprise 2.6 kernel) seen an application cause a
>> kernel deadlock in such a way that it would act like this if / and/or /var
>> deadlocked this way.....if you can get it to deadlock with a tty screen up and
>> get the sysrq keys to report various things you should be able to tell it was a
>> deadlock.
>>
>> You might also see if you can keep a ssh session (or 2 or 3) open and see how
>> good or bad it works when it happens again.
> 
> That was the plan (i.e., keep an SSH session up) last night.  Except
> that my laptop decided to go to sleep and lost the connection.  By the
> time I found out about it in the morning it's too late.  Darn Windows.
>  (c:
> 
> Thanks for the responses.  So, is it particularly unstable to have
> separate / and /var on xfs?  Would it help if I split it in to / and
> /var/lib or / on ext3 and /var on xfs or even just have a single /
> partition on xfs?  Though I'd rather not to, I can rebuild this system
> if necessary.

The problem saw before had to do with 2 separate instances of an application 
doing a full disk sync at the same time, and with bad timing they would somehow 
deadlock the kernel ... all other non-xfs filesystems on the machine worked, 
nothing worked on the xfs filesystem when this happened, note that it would only 
happen on 1 machine out of 100 overnight all running the same thing, it each 
night it would happen again on another machine-removing the sync and/or 
switching the filesystem resulted in the problem no longer happening.  The point 
is that *ANY* change can result in you finding an odd bug, I only use XFS for 
large data type partitions as there is very little advantage for using XFS for 
other things (it is not faster, and xfs is less heavily used than ext3 so there 
are likely more issues to be found-so it is somewhat riskier-this is true of any 
other less heavily used filesystem also).     I do use XFS for my myth storage 
with LVM under it, just not for the system partitions.

                               Roger