[linux-lvm] mirror and snapshot incompatible
jbrassow at redhat.com
Wed Oct 29 15:06:41 UTC 2008
No, there isn't a reason LVM prevents it, other than we haven't gotten
to it yet. That being said... because we haven't gotten to it yet
also means there probably hasn't been a whole lot of testing of such a
configuration. Therefore, it's difficult to quantify the safety.
On Oct 28, 2008, at 7:32 PM, Yoav wrote:
> I know how to do it through device-mapper. I'm just worried that
> maybe there's a reason why lvm prevents it. Are you aware of such
> reason, or is it safe?
> Jonathan Brassow wrote:
>> It is possible to do all the things you are asking through device-
>> mapper... but there is no easy way to do it. (and LVM does not yet
>> have the capabilities to manage this yet either.)
>> On Oct 27, 2008, at 9:28 PM, Yoav wrote:
>>> According to lvcreate, a snapshot of a mirrored volume cannot be
>>> created ("Snapshots and mirrors may not yet be mixed"). However,
>>> devmapper does not seem to have the same limitation when used
>>> directly (not through lvm).
>>> Is there a current reason for lvcreate to enforce this rather
>>> harsh limitation?
>>> What are the risks I'm taking by manually creating a dm-snapshot
>>> from a dm-mirror device? (of course I'm also replacing the dm-
>>> mirror device with a snapshot-origin of the actual dm-mirror
>>> If there is an actual reason for preventing this, what is the
>>> suggested way to consistently backup a mirror volume? Is there a
>>> way to temporarily take one of the mirror "legs" (mimage devices)
>>> offline in order to back it up, and resync it later?
>>> linux-lvm mailing list
>>> linux-lvm at redhat.com
>>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>> linux-lvm mailing list
>> linux-lvm at redhat.com
>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> linux-lvm mailing list
> linux-lvm at redhat.com
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
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