Re: [PATCH] btrfs: raid56: Use correct stolen pages to calculate P/Q

From: Christoph Anton Mitterer <calestyo@scientia.net>
To: Adam Borowski <kilobyte@angband.pl>
Cc: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>,
	Goffredo Baroncelli <kreijack@inwind.it>,
	Qu Wenruo <quwenruo@cn.fujitsu.com>,
	linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] btrfs: raid56: Use correct stolen pages to calculate P/Q
Date: Tue, 29 Nov 2016 15:24:54 +0100	[thread overview]
Message-ID: <1480429494.3155.7.camel@scientia.net> (raw)
In-Reply-To: <20161129073526.GA2441@angband.pl>

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On Tue, 2016-11-29 at 08:35 +0100, Adam Borowski wrote:
> I administer no real storage at this time, and got only 16 disks
> (plus a few
> disk-likes) to my name right now.  Yet in a ~2 months span I've seen
> three
> cases of silent data corruption

I didn't meant to say we'd have no silent data corruption.
OTOH, we cannot have had many of them, since the storage management
software itself has another layer of checksumming.

What I meant to say is that we likely never had such a scenario
described by Zygo, where e.g. broken HDD controller memory would cause
corruptions (and which would be then bad in case of auto-RAID-repair-
on-read).
Cause IMO such memory issues would rather soon be noticed.

Cheers,
Chris.

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