[mythtv-users] Consequences of drive failure

tortise tortise at paradise.net.nz
Wed Dec 5 08:33:55 UTC 2012


On 5/12/2012 8:29 a.m., Nick Rout wrote:
>
>
> On Wed, Dec 5, 2012 at 8:27 AM, Nick Rout <nick.rout at gmail.com
> <mailto:nick.rout at gmail.com>> wrote:
>
>
>
>     On Wed, Dec 5, 2012 at 3:11 AM, Mike Perkins
>     <mikep at randomtraveller.org.uk <mailto: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.
>
>
> Like this is what I mean: http://jaycar.co.nz/productView.asp?ID=XC4833
>

As I'd filled my four SATA ports I added a 
http://www.sunix.com.tw/product/sata1414.html for its speed and still 
not too expensive.  SATAIII's are also available, and possibly not that 
much more....


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