My tool working among 100 disks, some of them may attach or detach from the server during the tool running. I want to use disk's UUID as disk's id, and I got the question: If some disk disk_1 got a UUID, say 32c8da8b-e6d5-9a85-5cfc-1a8b59535263. When it's space full, I detached the disk and formatted it (mkfs.ext3), then re-attach to machine, will it's UUID change?
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coanor
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What's your tool? – ewwhite Mar 31 '15 at 12:19
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A filesystem's UUID is generated by mkfs, so a reformat will change the UUID.
One option is to create a label when you make the filesystem and look in /dev/disk/by-label rather than /dev/disk/by-uuid. An advantage of using a label is that you can re-label a filesystem after the fact if you need to. A disadvantage is that you are now responsible for maintaining the labels and preventing collisions.
Bandrami
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The first part is right, the UUID will change. But I'm not sure a label is a good id. There is a limit to the number of characters a label may have, so ensuring uniqueness would require some discipline. – hookenz Mar 31 '15 at 05:30
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If there is no specific reason for exclusively using UUID, you might consider alternatives like using /dev/disk/by-partuuid.
It relies on information stored in the GPT rather than in the partition itself, so the identifier should remain fixed when you only reformat the partition.
/dev/disk/by-id might also be interesting, it uses the hardware serial number. However, the controller type is part of the ID-string, so that might be a problem if you attach your disks differently each time.
source: https://wiki.archlinux.org/index.php/persistent_block_device_naming
Slizzered
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