From: Wol's lists <antlists@youngman.org.uk>
To: Marc MERLIN <marc@merlins.org>, Phil Turmel <philip@turmel.org>,
Kay Diederichs <kay.diederichs@uni-konstanz.de>
Cc: Andreas Klauer <Andreas.Klauer@metamorpher.de>,
Adam Goryachev <mailinglists@websitemanagers.com.au>,
Roger Heflin <rogerheflin@gmail.com>,
linux-raid@vger.kernel.org
Subject: Re: force remapping a pending sector in sw raid5 array
Date: Fri, 9 Feb 2018 22:07:57 +0000 [thread overview]
Message-ID: <3345d6f0-80d0-bfaf-9974-a7472d499117@youngman.org.uk> (raw)
In-Reply-To: <20180209212252.GN9565@merlins.org>
On 09/02/18 21:22, Marc MERLIN wrote:
> Interesting. I figured once a sector went pending once, it would not actually be re-used and
> be remapped on the next write. Seems like it didn't happen here.
Because there's all sorts of reasons a sector can go pending.
My favourite example is to compare it to DRAM. DRAM needs refreshing
every couple of seconds, otherwise it loses its contents and cannot be
read, but it's perfectly okay to rewrite and re-use it.
Likewise, the magnetism in a drive can decay such that the data is
unreadable, but there's nothing actually wrong with the drive. (If the
data next door is repeatedly rewritten, the rewrite can "leak" and trash
nearby data ...) The decay time for that should be years.
The problem of course is when the problem has a decay time measured in
minutes or hours. The rewrite succeeds, so the sector doesn't get
remapped, but when you next read it it has died :-(
Cheers,
Wol
next prev parent reply other threads:[~2018-02-09 22:07 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-06 18:14 force remapping a pending sector in sw raid5 array Marc MERLIN
2018-02-06 18:59 ` Reindl Harald
2018-02-06 19:36 ` Marc MERLIN
2018-02-06 20:03 ` Andreas Klauer
2018-02-06 21:51 ` Adam Goryachev
2018-02-06 22:02 ` Marc MERLIN
2018-02-06 22:31 ` Roger Heflin
2018-02-06 22:46 ` Marc MERLIN
2018-02-07 4:29 ` Marc MERLIN
2018-02-07 9:42 ` Kay Diederichs
2018-02-09 19:29 ` Marc MERLIN
2018-02-09 19:57 ` Kay Diederichs
2018-02-09 20:02 ` Roger Heflin
2018-02-09 20:13 ` Phil Turmel
2018-02-09 20:29 ` Marc MERLIN
2018-02-09 20:44 ` Phil Turmel
2018-02-09 21:22 ` Marc MERLIN
2018-02-09 22:07 ` Wol's lists [this message]
2018-02-09 22:36 ` Marc MERLIN
2018-02-09 20:52 ` Kay Diederichs
2018-02-11 20:52 ` Roger Heflin
2018-02-09 21:17 ` Kay Diederichs
2018-02-10 21:43 ` Mateusz Korniak
2018-02-11 15:41 ` Marc MERLIN
2018-02-11 16:41 ` Marc MERLIN
2018-02-11 17:13 ` Phil Turmel
2018-02-11 18:02 ` Wols Lists
2018-02-12 10:43 ` Mateusz Korniak
2018-02-12 15:29 ` Phil Turmel
2018-02-12 16:49 ` Marc MERLIN
2018-02-12 17:16 ` Phil Turmel
2018-02-12 17:30 ` Marc MERLIN
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