[Discuss] lvm snapshot cloning

[tmetro-blu at vl.com (Tom Metro)]

markw at mohawksoft.com wrote:
> Suppose you have a 1TB hard disk. How on earth do you back that up? 
> Think now if you want to pipe that up to the cloud for off-site backup.
> 
> The snapshot device "knows"
> what is different. You don't have to really backup 1TB every time, you
> only have to backup the changes to it since the last full backup.

If you are at the point of considering developing software to do this,
instead of just using off-the-shelf solutions, then you should consider
using inotify[1]. I believe using this library you could log to a
database the inodes that have been altered over a given period of time,
which another tool could then use to package up the data and send it to
your local or remote backup server.

Of course without snapshots you'd needs to take other steps to insure
consistency, if that matters for your application.

Seems DRBD[2] would be another way to address this, though not practical
for a remote backup server, as it'll send every change to the remote
server in real time.

Generally though, it seems like you are trying to re-invent ZFS, which
does both the snapshotting you want, as we'll as communicating
differential changes to a remote server. But I understand your
objections to ZFS.

1. https://github.com/rvoicilas/inotify-tools/wiki/
2. http://www.drbd.org/


> I can't give too much away...

Why? Developing something you plan to patent? Turn into a commercial
product and you want to keep the technology a trade secrete?

If those don't apply, then why not detail your scheme? Better to idea
vetted before you've invested a lot of time into building it.

 -Tom

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/