On 03/24/2011 08:23 AM, Hannes Reinecke wrote: > That is the approach I've been following for SUSE. > The UUID is assumed to be of this syntax: > > <type>-<identifier> There were several discussions, I think even unofficial definition tries but nobody documented that properly. So thanks for opening this here, it should be formalized (Alasdair?). What I remember from discussions: - all devices should set DM-UUID (not required still though) (btw available now in sysfs /sys/block/dm-X/dm/uuid in udev db, no need to use dm-ioctl) - everything is supposed to set a prefix to identify subsystem (owner) - DM-UUID can contain multiple namespaces - first part (prefix) says which the second part belongs to (e.g. CRYPT-PLAIN-blabla - CRYPT is says it was cryptsetup namespace, it is up subsystem to handle content, here we can parse crypt device type from it it for example.) - you can stack it (like partition/kpartx over other subsystem) (problem of prefix separator, now we will get probably something like part1-CRYPT-LUKS-00000000...) - kpartx uses prefix in format (part%N- where N is part number - my opinion it is bug but that up to discussion. My suggestion is to use KPARTX-part%N*) - some uses lowercase here - there is limit of 128 characters for DM-UUID (so stacking should handle this somehow) To my knowledge, these prefixes are in the wild: LVM- (lvm2) DMRAID- (dmraid) CRYPT- (cryptsetup) mpath- (multipath) part%N- (kpartx) Milan -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
