[mythtv-users] Consequences of drive failure

[Nick Rout]

On Wed, Dec 5, 2012 at 3:11 AM, Mike Perkins
<mikep at randomtraveller.org.uk>wrote:

> On 03/12/12 21:14, Michael Watson wrote:
>
>> On 3/12/2012 7:19 PM, Simon Hobson wrote:
>>
>>>
>>> As to copying your drive, my technique is this :
>>> Install the new drive in the system along side the existing one - you
>>> can now
>>> let the system continue running as normal.
>>> Partition & format as required, mount somewhere on the filesystem. Use
>>> rsync
>>> to copy the recordings from the old drive to the new one. You can do
>>> this in
>>> batches if you want, stopping before the backed has to do any Myth
>>> related
>>> work (eg recording or serving up frontends).
>>> When ready to make the switch, stop the backend, run the rsync copy
>>> again to
>>> get the replacement drive fully up to date, make any changes that might
>>> be
>>> needed to fstab etc, shutdown, remove the old drive and start up.
>>>
>>>  I would add the new drive, create filesystem and mount, add the new
>> drive to the
>> default storage group, and remove faulty drive from the storage group, so
>> no new
>> recordings will be written to the old drive, (but you will not be able to
>> access
>> the recordings on the old drive from within myth unless you create a new
>> storage
>> group with the old drive included).
>>      Copy the recordings over using rsync, but precede the rsync command
>> with
>> "ionice -c3", and let the copy run its course.  Once done, modify fstab to
>> include new drive and remove the old drive, shutdown and physically
>> remove old
>> drive.
>>      Power up, run find_orphans.py to clean up any missing recordings.
>>
>>  So, what is going to happen when your rsync operation meets the first
> defective sector?
>
> As it happens I have no intention of attempting any of this with the
> existing server host, (i) I would expose the other drives to potential
> operator error (ii) there are no free SATA slots which means more potential
> error juggling drives around (iii) every time I boot the server mythbackend
> will start and try to do things to the disks.
>
> There is a minor issue I have: the two old drives have the same geometry,
> the two new drives do as well, but the old drives have 512-byte sectors,
> the new ones have 4096-byte sectors. My plan is this:
>
> Remove good old drive, mount with new drive in spare host. Rsync files
> across. Put new drive into MBE slot where good drive was. (Er, fix fstab
> for new UUIID.)
>
> Remove bad old drive, mount into spare host alongside good old drive (same
> geometry). Use dd_rescue to bit-copy from bad to good. When happy with
> result remove bad old drive.
>
> Put remaining new drive in spare host, rsync from good old drive to new
> drive. Remove new drive and put into MBE.
>
> ??? Profit!
>
>
Sounds like it will work, but it will be MUCH faster if you can use a sata
port on your motherboard, or even get one of those usb to sata connectors
and plug it in the back. I took my backend offline while doing it, and
simply temporarily decommissioned one drive that wasn't involved in / or
the faulty drive, juggling the others as needed.

As you say UUID is the way to go :)



> --
>
> Mike Perkins
>
>
> ______________________________**_________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://www.mythtv.org/mailman/**listinfo/mythtv-users<http://www.mythtv.org/mailman/listinfo/mythtv-users>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.mythtv.org/pipermail/mythtv-users/attachments/20121205/8deb7e6e/attachment-0001.html>