>>>>> Karel Zak <kzak@xxxxxxxxxx> writes: >>>>> Ivan Shmakov <ivan@xxxxxxxxxxxxxx> writes: >>> GPT contains a supposed to be unique “Disk GUID” field, which allows >>> for the media bearing such a partition table to be identified. > The devel version of libblkid from util-linux-ng supports partition > tables parsing, and the partition name (GPT nad Mac) and partition > UUID (only GPT) are exported to udev. I don't quite understand how udev is tied here, but please note that the UUID I was talking above is the one associated with the partition table as a whole, not with a particular partition. (Huh? util-linux-ng has its own libblkid? And, BTW, any chance of having the changes accepted into e2fsprogs?) Such a UUID allows for removable media to be identified, which, in turn, allows for automated backups for such media. (Consider, e. g., that one has a bunch of bootable USB flash drives. From time to time, the OS'es are upgraded; and there may be problems with newer versions. The possibility of restoring the bootable image to the state it had at a certain time could then become extremly handy.) (Actually, I've just finished with the design of such a backup scheme, and it relies on the media — or partition table — UUID's, Sleuthkit and, to preserve disk space, Jigdo. Hopefully I'd be able to describe it at my “hacks collection” [1] soon.) [1] http://lhc.am-1.org/lhc/users/ivan_shmakov/ > For example: > # blkid -p -o udev /dev/sdb1 > ID_PART_ENTRY_SCHEME=gpt > ID_PART_ENTRY_NAME=ThisIsName > ID_PART_ENTRY_UUID=bc10cf1d-7e63-524c-8203-087ae10a820b > ID_PART_ENTRY_TYPE=a2a0d0eb-e5b9-3344-87c0-68b6b72699c7 > ID_PART_ENTRY_NUMBER=1 > In my TODO list is to support partition identifiers for standard > operations like mount/fsck, something like: > # mount PARTUUID=bc10cf1d-7e63-524c-8203-087ae10a820b /mnt > or > # mount PARTLABEL=ThisIsName /mnt > Comments? Well, to my mind, allowing UUID's that are stored in the partition table could be useful in two cases: • the filesystem contained on a partition doesn't allow for a UUID; • the filesystem is ought to be re-initialized (either to the same filesystem type or any other one) from time to time. Although I consider both of the above somewhat unlikely in my current practice, I don't see any harm of having such a feature “just for a case”. The labels are a bit useless, to my mind, since when one does mount(8) or fsck(8) by hand, it's usually when one does it with the medium attached to a host other than it was usually attached to. There, a name clash is quite likely. -- FSF associate member #7257
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