[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [linux-lvm] ANNOUNCE: an experimental implementation of snapshot merging




Is this change meant to add cluster support for merging?  I had
been under the assumption that merging was already a feature of
snapshots.

What is the difference between the current implementation using
lvremove (which I assumed was where the COW blocks were merged back
into the original volume) and lvconvert as below?  Why was this
functionality not kept in lvremove?

Mikulas Patocka wrote:
Hi

Here I release the first experimental implementation of snapshot merging. Merging allows you to copy data in snapshot back to the origin device. Once merging starts, it runs on background. When the merging finishes (you see "0%" with "lvs" command), you should remove the merging snapshot with lvremove command.

The userspace will still be changed, the kernel is already finished (there are no known bugs in the kernel, I'm curious about the unknown ones :)

Merging is initiated with "lvconvert -M vg/lv_snapshot" command. When you initiate merging, make sure that the origin device is not mounted. Snapshot can be mounted while it's merging is initiated.

During merging, aby reads and writes to the origin device are identical to accesses to the merging snapshots.

There may be multiple snapshots while one of them is being merged --- exceptions in other snapshots are being allocated and there snapshots are kept stable.

Don't try to concurrently merge more than one snapshot (the kernel refuses to do it, the userspace tools don't know about it --- the userspace will be rewritten anyway).

The patches are at:
http://people.redhat.com/mpatocka/patches/
The patches are for 2.6.26-rc4

(besides merging, there are some other bugfixes, I made for the kernel)

Mikulas

_______________________________________________
linux-lvm mailing list
linux-lvm redhat com
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

--
Steeve McCauley
Director of Research and Development
Rackable Systems
407 McGill Street, Suite 1002
Montreal, Quebec, H2Y 2G3 (Canada)
Tel: 514-288-3343
http://www.rackable.com
:wq


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]