From: Johann Lombardi <johann@whamcloud.com>
To: Eric Sandeen <sandeen@redhat.com>
Cc: linux-ext4@vger.kernel.org, Andreas Dilger <adilger@whamcloud.com>
Subject: Re: [PATCH] ext4: add support for multiple mount protection
Date: Tue, 12 Apr 2011 17:11:41 -0400 [thread overview]
Message-ID: <20110412211141.GA4244@neo> (raw)
In-Reply-To: <4DA4B885.6020004@redhat.com>
On Tue, Apr 12, 2011 at 03:39:33PM -0500, Eric Sandeen wrote:
> There was a lot of skepticism about this last time, and I imagine there still is...
MMP has absolutely no overhead if you don't turn it on. HA configurations (e.g. for NFS/CIFS servers) are very common out there.
Don't you think that MMP could be used in conjunction with Red Hat Cluster Suite to avoid corrupting the backend filesystem when things go wrong?
> 400 new lines of kernel code for this, and if the other machine is hung up for 5 seconds and doesn't update, it can still be multiply-mounted anyway, right?
>
> BUG: soft lockup - CPU#0 stuck for 10s! anyone? :(
If the kmmpd thread misses some MMP sequence updates, it reads the MMP block and calls ext3_error() if the sequence was updated behind its back.
Johann
next prev parent reply other threads:[~2011-04-12 21:11 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-12 18:04 [PATCH] ext4: add support for multiple mount protection Johann Lombardi
2011-04-12 19:20 ` Bernd Schubert
2011-05-02 13:43 ` Johann Lombardi
2011-04-12 20:39 ` Eric Sandeen
2011-04-12 21:08 ` Andreas Dilger
2011-04-12 21:11 ` Johann Lombardi [this message]
2011-04-12 21:41 ` Bernd Schubert
2011-04-12 21:44 ` Eric Sandeen
-- strict thread matches above, loose matches on Subject: below --
2011-05-02 8:11 MMP update Johann Lombardi
2011-05-02 9:36 ` [PATCH] ext4: add support for multiple mount protection Johann Lombardi
2011-05-23 2:19 ` Ted Ts'o
2011-05-14 0:38 Johann Lombardi
2011-05-24 21:47 ` Ted Ts'o
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