I don't think the "same disk" option has been in before. You used to
have to use Solstice disksuite and prepare a separate log partition in
advance (which is a pain in itself when trying to carve up a large
disk array and you only have a stupid 7 slot disklabel to play with).
With Solaris 2.^H^H7, it's just a mount time option to add a log on
the fly on the same partition. You lose performance though over having
a separate spindle for logging.
While I'm here: an idea for providing a snapshot capability to any
block device (allowing you to snapshot then backup any fs you like).
A fake block device /dev/snap which you connect to the
device-to-be-snapshotted on one side and to a spare block device on
the other side (either a spare partition or a /dev/loop on a file).
snap keeps a dirty bitmap and a sparse block structure on the spare
block device. Writes to snap mark the block in the dirty bitmap and
store the original block in the sparse structure. Reads from snap
check the dirty bitmap and read from the original or the sparse block
map.
Usage would be a bit like the loop block device. When you want to
snapshot device /dev/sda1 on spare partition /dev/sdb2 you do
snapsetup /dev/snap0 /dev/sda1 /dev/sdb2
and that starts dribbling the originals of any blocks changed on
/dev/sda1 to /dev/sdb2 (stored sparsely). Then you backup /dev/snap0.
When you've finished, you stop the snap0 device. Has anyone else got
something around that does that or should I try to persuade/help
someone to do it?
--Malcolm
-- Malcolm Beattie <mbeattie@sable.ox.ac.uk> Unix Systems Programmer Oxford University Computing Services- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/