From mboxrd@z Thu Jan  1 00:00:00 1970
From: Matthias Urlichs <matthias@urlichs.de>
Subject: Re: Re-map disk sectors in userspace when rewriting after read
 errors
Date: Tue, 15 Sep 2009 07:29:18 +0000 (UTC)
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On Tue, 15 Sep 2009 08:13:08 +0100, Alex Butcher wrote:

> IME, discs don't remap after read errors, only on writes.

Some may remap after recoverable read errors. However, the RAID code
does (I assume - see below) rewrite the data -- which the disk happily 
acknowledges  -- only to report the very same error next time that spot's 
being read. :-(

> Are you sure that refresh-writes triggered by read errors are expected
> behaviour of md's RAID5/6 mode?

Not 100%, no -- but recovering the data but otherwise ignoring the error 
(other than increment the error counter) would be a level of foolishness 
I won't assume of the RAID code's authors.

-- 
Matthias Urlichs