Re: [Devil-Linux-discuss] Support for LVM restore from snapshot

[Heiko Z. <he...@zu...>]

Quoting Dominic Raferd <dl...@ed...>:

> A very happy New Year to all DL developers and users!
>
> LVM2 since 2.02.58 supports an option (lvconvert --merge) to merge back
> an LVM snapshot to an original source. This allows to you create a
> snapshot, then make 'dangerous' changes to the original source, and
> afterwards, if unhappy with the changes, simply restore the snapshot to
> recover the original data.
>
> This is potentially very useful (as in, how come LVM didn't always do
> this?) and is supported by LVM 2.02.72 as found in DL 1.4 (and I think
> 1.4.1 tho I am not yet using it, sorry), but I don't think it will work
> because the man page [for LVM 2.02.76] says "To check if your kernel
> supports this feature, look for 'snapshot-merge' in the output of
> 'dmsetup targets'" And when I do this in DL I don't see snapshot-merge
> listed.
>
> Info about kernel device-mapper snapshot support here:
> http://alinux.tv/Kernel-2.6.34/device-mapper/snapshot.txt
> LVM2 changelog here: ftp://sources.redhat.com/pub/lvm2/WHATS_NEW
>
> I confess I haven't tested it because my DL machine is a production
> system and I don't want to risk upsetting it. Is someone able to try it
> on a test DL system by creating an LVM snapshot (e.g. of /home), making
> changes to the original and then merging back the snapshot? If the
> kernel support is critical and is missing then I presume this will fail,
> whether safely or not I have no idea.
>
> If the kernel support is needed, can I ask for this option
> (snapshot-merge) to be added to DL kernel for the next mini-release,
> please (and upgrade LVM to 2.02.79)? I can put this request on Mantis if
> preferred...

Unfortunately we froze the Kernel release to 2.6.32.x, since this is  
the long-term stable.

The next major release of DL with have the latest kernel, but we're  
not even anywhere close to an alpha release.

The only way for you to get is, is to create a custom version of DL  
with the latest 2.6 kernel.

-- 

Regards
   Heiko Zuerker
   http://www.devil-linux.org


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