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From: "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>
To: device-mapper development <dm-devel@redhat.com>
Subject: Re: Snapshots
Date: Wed, 19 Dec 2007 15:59:25 -0500	[thread overview]
Message-ID: <4769862D.6090403@ce.jp.nec.com> (raw)
In-Reply-To: <47694A05.9090202@cfl.rr.com>

Phillip Susi wrote:
> Jun'ichi Nomura wrote:
>> LVM2 does it by putting a linear mapping on top of the origin device.
> 
> How does this work?  I'm trying to figure out the whole locking business
> and it seems that mounting the device, or using it as a target in a dm
> table place an exclusive lock on the device, so how can you add a linear
> mapping to the origin device, if it is already used as a target in the
> snapshot device, and thus locked?

So, you have to put the linear mapping *before* that.
Then, the top-level block device will be locked but you can
still change the underlying mappings.

Thanks,
-- 
Jun'ichi Nomura, NEC Corporation of America

  reply	other threads:[~2007-12-19 20:59 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-12-18 19:57 Snapshots Phillip Susi
2007-12-18 22:38 ` Snapshots Jun'ichi Nomura
2007-12-19 16:42   ` Snapshots Phillip Susi
2007-12-19 20:59     ` Jun'ichi Nomura [this message]
2007-12-20 19:45       ` Snapshots Phillip Susi
2007-12-22  1:28         ` Snapshots Jun'ichi Nomura
  -- strict thread matches above, loose matches on Subject: below --
2017-09-15 17:28 snapshots Two Spirit
2017-09-15 17:37 ` snapshots Sage Weil
2017-09-15 17:42   ` snapshots Two Spirit
2017-09-15 18:25     ` snapshots Sage Weil
2017-09-15 18:59       ` snapshots Eric Eastman
2017-09-15 19:33         ` snapshots Wyllys Ingersoll
2017-09-15 20:22           ` snapshots Sage Weil
2017-09-15 21:23             ` snapshots Wyllys Ingersoll

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