[dm-devel] Snapshots
Jun'ichi Nomura
j-nomura at ce.jp.nec.com
Wed Dec 19 20:59:25 UTC 2007
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
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