Re: Proactive Drive Replacement

[Mario 'BitKoenig' Holbe <Mario.Holbe@TU-Ilmenau.DE>]

David Lethe <david@santools.com> wrote:
> is correctly called the "SMART selective
> self-test routine".   By the way, this is an OFF-LINE scan.  

short, long, conveyance and selective tests are all offline.

> So bottom line, Mario is correct in that there is a way to get a PARTIAL
> list of bad blocks, if you have a disk
> that supports this command, and you're willing to run an off-line scan
> (not practical or a parity-protected RAID 
> environment).

Most modern (ATA) disks support "Suspend Offline collection upon new
command". Well, the tests take notably longer on a loaded disk and
(low-frequent) requests to that disk take notably longer as well
(high-frequent requests just keep the test suspended), but it works.

> It is possible that some vendor has implemented a SATA ON-LINE bad block
> scanning mechanism that reports results and
> doesn't kill I/O performance.  It would have to give full list of bad
> blocks, or at least startingblock + range.
>
> That would be wonderful as you could just read the list on regular
> interval and rebuild stripes as necessary. You'd have
> Self-healing parity.

echo check > /sys/block/mdx/md/sync_action

That's indeed way more powerful than any attempt to rely on any
S.M.A.R.T. thingy.


regards
   Mario
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