lvmsync | Synchronise LVM LVs across a network

To run lvmsync, you'll need to have a working installation of Ruby 1.8 (or later) on both the machine you're transferring from, and the machine you're transferring to. On the source, you'll need vgcfgbackup (which is part of the core LVM2 toolset), and if you want to deal with thin snapshots, you'll also need thin_dump (which is part of the "thin provisioning tools" which are highly recommended for anyone working with thin-provisioned LVs). For transferring dumps between machines, you'll need SSH installed and working between the two machines. Installing lvmsync itself is easiest using Rubygems: gem install lvmsync. This will install all the dependencies and (presumably) put the lvmsync command itself in root's PATH. If for some reason you want to install it all by hand, you'll need to copy the contents of lib/ into a directory in your Ruby library path, copy bin/lvmsync to somewhere on your PATH, and install the treetop and git-version-bump gems.
If you need to transfer an LV between different VGs on the same machine, then running everything through SSH is just an unnecessary overhead. If you instead just run lvmsync without the <destserver>: in the destination specification, everything runs locally, like this:. All other parts of the process (creating the snapshot, doing the initial data move with dd, and so on) are unchanged. As an aside, if you're trying to move LVs between PVs in the same VG, then you don't need lvmsync, you need pvmove.