I recently added a new disk to my system, and while I can see it after rescanning, it unfortunately doesn't have a UUID. I've tried using the commands `pvscan` and `pvscan --cache`, but the UUID still doesn't show up. The only time it displays the UUID is after I reboot the system. Is there a way to resolve the missing UUID issue without needing to restart the machine? I've looked online, and most of the solutions I found involve those same commands or just doing a rescan.
3 Answers
UUIDs need to be written to the drive, and they won't just appear out of nowhere. If there are no physical volumes (PVs) created on that disk, then `pvscan` won't show a UUID for it. After you've added the disk, if the system doesn't automatically recognize it, try running a command to rescan the SCSI bus, like `for tmp in /sys/class/scsi_host/host*/scan; do echo '- - -' >> "$tmp"; done`. This should help the OS see the new drive without needing a system reboot.
Have you checked the `/dev/disk/by-uuid` directory? It could give you some insight into what UUIDs are currently recognized by your system. Sometimes, drives take a bit to register properly without a reboot.
Just a note: if the new disk is blank and doesn't have a partition table yet, it won't have a UUID. You'd need to run `pvcreate` on it to format it as a physical volume, which will generate the UUID at that point. Would you consider partitioning first, or are you looking to use the entire disk as it is?
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