[mythtv-users] Recommended Disk Test

[Jeff Siddall]

On 01/13/2015 02:40 PM, Dick Steffens wrote:
> My MythTV box is scheduled to go into the shop on Monday because of an
> intermittent freeze. The symptom is that infrequently (once every two
> weeks or so, but not regularly) I'll either turn on the TV and get no
> response to a keyboard even though my wallpaper is there, or I'll try to
> look at a MythWeb page from another machine but won't be able to
> connect, or (this happened only once during one of the NFL games last
> Sunday) the system will freeze during a show. Recovery requires a power
> cycle. Attempts to SSH into the machine fail due to SSH being unable to
> find it.
>
> Before I take it in to the hardware gurus I want to be sure I've run
> appropriate tests. I ran memtest with no errors. What disk test should I
> run that will be a non-destructive test? And, when I run it, do I need
> to have the backend and MySQL shut down?
>
> Are there any other tests I can run to try to narrow down the problem?
>
> Thanks.

Random freezes can be caused by all sorts of issues.  Most common (in 
order of frequency I have seen them) are:

1. RAM: you sometimes need to run memtest for days to see the failure. 
If you have multiple sticks, try reversing the order or removing one at 
a time to see if anything behaves differently.

2. Power supply: easy to change and relatively inexpensive.  Not a bad 
idea to have a spare one around anyway.

3. Bad caps: if you have a MB from a few years ago this is a common problem:

http://www.thenakedpc.com/dan/Bulging_Capacitors/close-up.jpg

...and they don't have to be leaking to cause system flakiness.

These can be replaced but are usually a bit tricky if you aren't good 
with a soldering iron.

If it's not one of those three things then it gets much harder.  If you 
have removable expansion cards you can try removing those one at a time 
to see if you can isolate the culprit.

At some point you will probably be better off just upgrading your 
CPU/MB/RAM and give up on what you have.  Don't forget you will likely 
need to rebuild your initrd to support the new hardware if you go this 
route.

Also, despite what others have said a failing hard drive doesn't cause 
kernel freezes.  Your system will certainly behave badly, but something 
will be responsive -- even if it is just the capslock light changing 
when you press caps lock.

Good luck!

Jeff