Op 20 mei 2015 16:51 schreef "Jan Kasprzak" <kas@xxxxxxxxxx>:
>
> Hi Ladislav,
>
> Ladislav Mate wrote:
> : > I have a RAID-5 volume of 8 physical disks. One of these disks failed the SMART
> : > self-test with an unreadable block error. Unfortunately I have discovered
> : > that there is _another_ bad block on another disk. It is a different block,
> : > so the RAID-5 volume as a whole is still working. But as a whole, the
> : > RAID-5 volume has at least two unreadable sectors on two different disks.
> : >
> : > What is the best way to replace these two failing disks one by one without
> : > the loss of data? I cannot mdadm --fail one of them, because the
> : > subsequent rebuild on a new disk would fail on reading the other bad block.
> : >
> : > I would like to add the ninth drive to the RAID-5 volume, and put a replica
> : > of one of the failing drives to it. Then remove the just-replicated drive,
> : > and do the same with the other failing drive.
> : When you take a look in mdadm man page and search for --replace you'll find what you are looking for.
> :
> : --replace
> : Mark listed devices as requiring replacement. As soon as a spare is available, it will be rebuilt and will replace
> : the marked device. This is similar to marking a device as faulty, but the device remains in service during the recov-
> : ery process to increase resilience against multiple failures. When the replacement process finishes, the replaced
> : device will be marked as faulty.
> :
> : --with This can follow a list of --replace devices. The devices listed after --with will be preferentially used to replace
> : the devices listed after --replace. These device must already be spare devices in the array.
>
> OK, this seems to be a way to go.
>
> Unfortunately, the system in question is too old,
> and its mdadm does not know about the --replace option, according to
> mdadm --manage --help. So I will look for a newer mdadm and hope the old
> kernel of that system supports the mdadm --replace.
>
You'll need kernel version 3.3+ to support advance replacement.
Kind regards,
Caspar
> Thanks!
>
> -Yenya
>
> --
> | Jan "Yenya" Kasprzak <kas at {fi.muni.cz - work | yenya.net - private}> |
> | New GPG 4096R/A45477D5 -- see http://www.fi.muni.cz/~kas/pgp-rollover.txt |
> | http://www.fi.muni.cz/~kas/ Journal: http://www.fi.muni.cz/~kas/blog/ |
> Smart data structures and dumb code works a lot better
> than the other way around. --Eric S. Raymond
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