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From: Christoph Anton Mitterer <calestyo@scientia.net>
To: Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: [BUG] Btrfs scrub sometime recalculate wrong parity in raid5
Date: Mon, 27 Jun 2016 18:39:57 +0200	[thread overview]
Message-ID: <1467045597.6613.9.camel@scientia.net> (raw)
In-Reply-To: <5770AD08.3050201@gmail.com>

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On Mon, 2016-06-27 at 07:35 +0300, Andrei Borzenkov wrote:
> The problem is that current implementation of RAID56 puts exactly CoW
> data at risk. I.e. writing new (copy of) data may suddenly make old
> (copy of) data inaccessible, even though it had been safely committed
> to
> disk and is now in read-only snapshot.

Sure,... mine was just a general thing to be added.
No checksums => no way to tell which block is valid in case of silent
block errors => no way to recover unless by chance

=> should be included as a warning, especially as userland software
starts to automatically set nodatacow (IIRC systemd does so), thereby
silently breaking functionality (integrity+recoverability) assumed by
the user.


Cheers,
Chris-

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  reply	other threads:[~2016-06-27 16:40 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-25 12:21 [BUG] Btrfs scrub sometime recalculate wrong parity in raid5 Goffredo Baroncelli
2016-06-25 17:25 ` Chris Murphy
2016-06-25 17:58   ` Chris Murphy
2016-06-25 18:42     ` Goffredo Baroncelli
2016-06-25 22:33       ` Chris Murphy
2016-06-26  9:20         ` Goffredo Baroncelli
2016-06-26 16:43           ` Chris Murphy
2016-06-26  2:53   ` Duncan
2016-06-26 22:33     ` ronnie sahlberg
2016-06-26 22:38       ` Hugo Mills
2016-06-27  3:22         ` Steven Haigh
2016-06-27  3:21       ` Steven Haigh
2016-06-27 19:47         ` Duncan
2016-06-27  3:50       ` Christoph Anton Mitterer
2016-06-27  4:35         ` Andrei Borzenkov
2016-06-27 16:39           ` Christoph Anton Mitterer [this message]
2016-09-21  7:28 ` Qu Wenruo
2016-09-21  7:35   ` Tomasz Torcz
2016-09-21  9:15     ` Qu Wenruo
2016-09-21 15:13       ` Chris Murphy
2016-09-22  2:08         ` Qu Wenruo
2016-09-22  2:44           ` Chris Murphy
2016-09-22  3:00             ` Qu Wenruo
2016-09-22  3:12               ` Chris Murphy
2016-09-22  3:07           ` Christoph Anton Mitterer
2016-09-22  3:18             ` Qu Wenruo
2016-09-21 15:02   ` Chris Murphy
2016-11-04  2:10 ` Qu Wenruo
2016-11-05  7:23   ` Goffredo Baroncelli
  -- strict thread matches above, loose matches on Subject: below --
2016-07-12 21:50 [BUG] Btrfs scrub sometime recalculate wrong parity in raid5: take two Goffredo Baroncelli
2016-07-16 15:51 ` [BUG] Btrfs scrub sometime recalculate wrong parity in raid5 Jarkko Lavinen
2016-07-17 19:46   ` Jarkko Lavinen
2016-07-18 18:56   ` Goffredo Baroncelli
2016-08-19 13:17 Philip Espunkt

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