lazy mirror / live backup

[Eric Anderson]

On 04/21/07 05:02, Bernd Walter wrote:
> On Fri, Apr 20, 2007 at 09:04:11PM -0500, Eric Anderson wrote:
>> On 04/20/07 20:25, Mike Wolman wrote:
>>> On Sat, 21 Apr 2007, Bernd Walter wrote:
>>>
>>>> On Sat, Apr 21, 2007 at 01:38:31AM +0100, Mike Wolman wrote:
>>> Yea i use rsync and snapshots quite a bit, but unfortunately rsync works 
>>> at the filesystem level so you cant really get a bootable image of the 
>>> whole device.  It would be nice if this could be done without user 
>>> interaction, ie if the ggatec component of a mirror disappears and 
>>> reappears gmirror justs gets to work syncing things up.
>> rsync and it's like are great tools, but traversing the tree every time 
>> is not only slow and heavy handed, but it takes an enormous amount of 
>> memory (akin to fsck) for large file systems.  rsync isn't the right 
>> tool for lazy syncing.
> 
> Thich file tree?
> I was talking about a snapshot, which is a single file.
> 


Oh, I didn't realize you were recommending rsync'ing the snapshot file 
itself.  Wow.  That seems pretty brutal of a solution to me.  The only 
gain is the reduced data transferred over the net, and not the quicker 
sync time, less load on your source disks, etc.

I think everyone knows that there are some solutions to the problem. 
The problem is they are not good or elegant solutions.  What Mike is 
proposing is an elegant solution, that is slick and smooth, and simple.

Eric