From: Alasdair G Kergon <agk@redhat.com>
To: Takashi Sato <t-sato@yk.jp.nec.com>
Cc: "axboe@kernel.dk" <axboe@kernel.dk>,
"mtk.manpages@googlemail.com" <mtk.manpages@googlemail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"xfs@oss.sgi.com" <xfs@oss.sgi.com>,
"dm-devel@redhat.com" <dm-devel@redhat.com>,
"viro@ZenIV.linux.org.uk" <viro@ZenIV.linux.org.uk>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH 0/3] freeze feature ver 1.8
Date: Mon, 30 Jun 2008 14:54:33 +0100 [thread overview]
Message-ID: <20080630135433.GA22522@agk.fab.redhat.com> (raw)
In-Reply-To: <20080630212005t-sato@mail.jp.nec.com>
On Mon, Jun 30, 2008 at 09:20:05PM +0900, Takashi Sato wrote:
> Currently, ext3 in mainline Linux doesn't have the freeze feature which
> suspends write requests. So, we cannot take a backup which keeps
> the filesystem's consistency with the storage device's features
> (snapshot and replication) while it is mounted.
> In many case, a commercial filesystem (e.g. VxFS) has
> the freeze feature and it would be used to get the consistent backup.
> If Linux's standard filesytem ext3 has the freeze feature, we can do it
> without a commercial filesystem.
Is the following a fair summary?
1. Some filesystems have a freeze/thaw feature. XFS exports this to
userspace directly through a couple of ioctls, but other filesystems
don't. For filesystems on device-mapper block devices it is exported to
userspace through the DM_DEV_SUSPEND ioctl which LVM uses.
2. There is a desire to access this feature from userspace on non-XFS
filesystems without having to use device-mapper/LVM.
Alasdair
--
agk@redhat.com
next prev parent reply other threads:[~2008-06-30 13:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-30 12:20 [PATCH 0/3] freeze feature ver 1.8 Takashi Sato
2008-06-30 13:54 ` Alasdair G Kergon [this message]
2008-07-01 9:12 ` [dm-devel] " Takashi Sato
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