some thoughts about gmirror

[Mike Wolman]

>> Hi,
>> 
>> Currently I am using gmirror and ggated to run a live network mirror. 
>> Obviously this can cause problems if the server exporting the 'backup' 
>> device is offline then the mirror is broken - when the machines reconnect a 
>> full mirror sync takes place.  This is fine over gbit crossover and if the 
>> size of the mirror is only a few 100Gb.
>
>
> Personally, I think this would be a very useful feature.  This is sort of 
> like snapshots for GEOM, which would be useful in other ways too. GEOM 
> journaling, GEOM snapshots, and this lazy mirroring are all somewhat similar 
> it seems.
>
> Are you proposing to write such a feature?  Even if you can't code it, 
> writing up the design/specs might help someone actually implement it.
>
>
> Eric
>

My initial thoughts were for fast recovery from a non failed mirror device 
but realised it could be used for many other things from mobile users to 
remote asyncs.  I had not thought of using it for snapshots but i can see 
where your coming from - by simply keeping the changes you could rewind 
to any point in time without having to actually create a snapshot(s) 
beforehand.

I only wish my os/file system/geom knowledge was up to even specifying 
this, let alone my complete lack of c programming ability.

However I can try to put together a specification from a system admins 
perspective if that is of any help?

And of course i would be more than willing to test test test.

Mike.