From: Paul Clements <Paul.Clements@SteelEye.com>
To: Neil Brown <neilb@cse.unsw.edu.au>
Cc: linux-raid@vger.kernel.org
Subject: Re: [PATCH] md: fix device size calculation with non-persistent superblock
Date: Tue, 24 Feb 2004 10:27:55 -0500 [thread overview]
Message-ID: <403B6D7B.29A4B2A0@SteelEye.com> (raw)
In-Reply-To: 16442.42303.445148.394516@notabene.cse.unsw.edu.au
Neil Brown wrote:
>
> On Monday February 23, Paul.Clements@SteelEye.com wrote:
> > Neil,
> >
> > Currently, the device size calculation is not correct when hot-adding
> > devices to arrays with non-persistent superblocks. Device size is always
> > calculated as if there were a physical superblock on every device. The
> > attached simple change to hot_add_disk() fixes the problem.
>
> Hmm.. I had always assumed that non-persistent superblocks only worked
> for linear and raid0. I'm not sure I would trust any other
> configuration.
>
> Are you seriously using raid1 with non-persistent superblocks?
Yes, and this works fine in 2.4, as well. We opted for non-persistent
superblocks in order to support creation of raid1 mirrors over
partitions that already had filesystems or other data present (and yes,
we calculate the size of the new md device to make sure the existing
data will fit).
> How do you ensure reliable re-assembly after a device failure followed by
> shutdown?
There is a user-level clustering framework that sets up, monitors, and
takes down the mirror. Disk failures and other events are handled by
this framework.
--
Paul
next prev parent reply other threads:[~2004-02-24 15:27 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-23 2:41 SW RAID5 + high memory support freezes 2.6.3 kernel Pavol Luptak
2004-02-23 4:27 ` Neil Brown
2004-02-23 5:30 ` Andrew Morton
2004-02-23 13:35 ` Pavol Luptak
2004-02-23 14:05 ` syrius.ml
2004-02-23 16:57 ` [PATCH] md: fix device size calculation with non-persistent superblock Paul Clements
2004-02-24 1:13 ` Neil Brown
2004-02-24 15:27 ` Paul Clements [this message]
2004-02-25 21:39 ` [PATCH] raid1: abort resync if there are no spare drives Paul Clements
2004-03-03 0:21 ` Neil Brown
2004-03-03 2:47 ` Paul Clements
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