On Mon, 24 Oct 2011 22:12:14 +0200 Arkadiusz Miśkiewicz
<a.miskiewicz@xxxxxxxxx> wrote:
>
> kernelnewbies.org reports such feature for 3.1 kernel
>
> 1.9. Software RAID: Bad block management
> The MD layer (aka "Multiple Devices", aka software raid) has gained bad block
> management support: bad blocks will be added to a list, and the system will
> try not to use them. This feature requires an updated mdadm version.
>
> Which mdadm supports that?
>
mdadm-3.3 will support bad block management.
However it is not released yet.
You can get current code from
git://neil.brown.name/mdadm devel-3.3
It isn't released yet because
1/ I haven't found/made time to work on mdadm and integrate support
properly.
2/ The kernel isn't really quite read for full support.
If you have a bad block list, then a write error will not fail the drive but
will record the location of the write error.
This might be what you want. But if you have a hot-spare available it might
not be what you want - the current kernel code will never use a hot spare
until a drive fails really badly.
What it *should* do is "hot-replace". i.e. recover the data on to a spare
without first removing the device with the bad block. But the hot-replace
code isn't ready yet.
I expect hot-replace to be in linux-3.3 (for RAID4/5/6 at least) and I hope to
release mdadm-3.3 before then with full support for bad blocks and hot
replace.
For now if you use the devel-3.3 code to create a new array it will place a
bad-block-log on the array and the kernel will use that bad block log to
record failed blocks rather than failing the whole device.
If you want a device to be failed, you might have to explicitly do that
yourself with "mdadm /dev/mdX --fail /dev/sdY"
NeilBrown
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