[mythtv-users] Consequences of drive failure

[Michael T. Dean]

On 12/02/2012 05:22 PM, Nick Rout wrote:
> On Mon, Dec 3, 2012 at 8:41 AM, tortise wrote:
>> On 2/12/2012 8:32 a.m., Nick Rout wrote:
>>> On Dec 2, 2012 8:25 AM, "Mike Perkins" wrote:
>>>>   Okay. So I've discovered that one of the two 500Gb drives in my
>>>> recording storage group is failing, enough that I'm getting jumps during
>>>> playback and indecipherable error messages in dmesg.
>>>>
>>>>   I've ascertained that there is enough auto-expirable files in the
>>>> system that I can run on one drive until the newly-ordered ones arrive
>>>> next week, so I've pulled the SATA cable. It's not comfortable, but
>>>> doable, and the alternative is writing fresh recordings to a dying disk.
>>>>
>>>>   My question is, how does the system react when you take half the
>>>> recordings away? They are all still present in the database, but is
>>>> there any indication that they are or are not available for watching?
>>>
>>> I think there will be some error message when you try to play a missing
>>> recording. No other indication in the gui.
>> In mythweb | Recorded programs where the recordings not found the file
>> size is also shown with a "B" I think that would show in the case of a
>> removed drive for the relevant recordings but I've not tested that scenario.
>>
>> My thread on "Batch Download and Archive Recordings With Expanded File
>> Names" may be of interest as an interim backup option to at least harvest
>> the recordings with sensible file names to cover the transplant failing.
>
> Most of the files should be able to be moved off the drive. Mount them read
> only.
>
> Actually in the end I had to use dd or dd_rescue to make an image and then
> copied them off the image (the drive was quite badly broken as a result of
> stupid me ignoring the first sign of trouble - never again!)
>

If you mount a MythTV directory read only, you *must* remove that 
directory from /all/ Storage Groups to which recordings may be written 
or you will have failed recordings.  So, go into mythtv-setup, find the 
Storage Group(s) that contain the directory on the soon-to-be-read-only 
file system and delete that directory from the Storage Group 
definition.  Then, create a brand new Storage Group (i.e. Read Only or 
Archive or Temporary or whatever) and add that directory to that Storage 
Group.  When you do, MythTV will still be able to find the recordings in 
that new Storage Group, but since none of your Recording Rules specify 
that recordings should be written to that Storage Group, it will never 
cause recording failures.

Mike