From: Eric Sandeen <sandeen@sandeen.net>
To: Ewan Chalmers <ewan.chalmers@gmail.com>
Cc: xfs@oss.sgi.com
Subject: Re: Does XFS support the sync mount option?
Date: Thu, 12 Feb 2009 18:39:42 -0600 [thread overview]
Message-ID: <4994C14E.5090402@sandeen.net> (raw)
In-Reply-To: <884979c90902121546g35f594b1s592859ac7b832533@mail.gmail.com>
Ewan Chalmers wrote:
> Thanks for your detailed reply.
>
>> And "sync" only works if you turn drive write caches off or have
>> barriers enabled. There are many people out there that have systems
>> that are suseptible to fatal filesystem corruption that could be
>> triggered by doing this (because critical metadata is lost from
>> the volatile write cache on the drive when you power it off).
>
> According to the FAQ, barriers are enabled by default since 2.6.17.
That's kernel version
> I
> have 2.9.8,
that's xfsprogs version.
> so I guess barriers are enabled. I have checked and dmesg
> contains no errors relating to barriers.
>
> Also according the FAQ... "With a single hard disk and barriers turned
> on (on=default), the drive write cache is flushed before an after a
> barrier is issued. A powerfail "only" loses data in the cache but no
> essential ordering is violated, and corruption will not occur."
>
> So it sounds like pulling the plug on the disk should not cause
> corruption in this case (sync mount and barriers default enabled). Or
> am I just plain wrong?
It should not cause metadata corruption
> (BTW, I've done an xfs_repair which reported no errors.)
... which is what repair will check for.
-Eric
> Thanks,
> Ewan
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prev parent reply other threads:[~2009-02-13 0:40 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-05 14:43 Does XFS support the sync mount option? Ewan Chalmers
2009-02-06 23:05 ` Dave Chinner
2009-02-09 8:34 ` Michael Monnerie
2009-02-12 23:46 ` Ewan Chalmers
2009-02-13 0:39 ` Eric Sandeen [this message]
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