[linux-lvm] access or interface to list of blocks that have, changed via C.O.W.?

Bryn M. Reeves bmr at redhat.com
Fri Oct 5 09:26:32 UTC 2012

On 10/04/2012 04:02 PM, Mark Woodward wrote:
> On 10/04/2012 10:44 AM, Bryn M. Reeves wrote:
>> Really? I'd be surprised if it even builds against modern kernels or
>> device-mapper.
> Well.....
> The LVM2 code that ships with most distros still uses the old interfaces 
> and still (Ubuntu 12.04) seemst to create a COW file with SnAp

Yes; that's the traditional dm-snapshot target that has been in the
kernel for years. The Zumastor/ddsnap stuff was a separate project to
replace that using a new metadata format and target - they are not the
same and the Zumastor snapshot code was never merged in the kernel.

>> Snapshots using the thinp target use the metadata format described in
>> dm-thin-metadata.c.
> Where are these files to be found?

In drivers/md in the kernel sources - the dm-thin stuff was merged after
3.1 (October last year); see commits starting with 991d9fa.


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