lazy mirror / live backup

[Mike Wolman]

>> I'd like the ability to have gmirror do a more efficient re-silvering (or
>> re-syncing) of the mirror members when a planned disconnect occurs. This
>> would significantly reduce the mirror rebuild time for any component which
>> had been deactivated, for network mirrors using ggated devices this would
>> also reduce network usage and could be used for remote asynced mirrors
>> thus providing a live backup for laptops/workstations.

>Do you see that you are describing ZFS there?  Considering the status of
>ZFS right now, I think it is not worth really trying to implement such
>scheme in gmirror.

The problem with zfs is you cannot layer it as u can with the geom 
classes.

For example if you want to create a failover zfs storage pool, if you make 
the zfs pool out of gmirror devices with one being a local device and the 
other being a ggatec device.  You would then have your zfs raidz pool 
replicated on a remote host.  I do not think you can do this with zfs by 
itself as you are not able to layer raidz pool ontop of a load of zfs mirrors.

Mike.