Before the UUID method was introduced, cloning was not an issue.
This brings up a second issue. Assume that the cloning works using a hardware cloning device -- that has worked before between different vendor's physical hard drives of the nominally same capacity or that worked by cloning a smaller drive onto a larger drive and then formatting the "unformatted" larger portion, etc. (I have done this both with EIDE and SATA drives -- and SCSI long ago on rack-mounted systems.) What happens if one attempts to use the "old" drive in a, say, SATA to USB adapter that normally would allow a SATA drive to mount as a USB device?
As the internal harddrive and the USB mounted external hard drive have the same UUIDs (clones), there would be a conflict. (This approach did work before UUIDs, even with the same named partitions -- one manually mounted a /usr partition on the external drive under a mount point such as /usrusb, and the like -- new mount points for, say, /dev/sdc1 that had the same name -- /usr -- as /dev/sda1.)
Is there any similar "trick" for mounting an external hard drive via a USB interface (or any other such interface to a different standard) even though nominally each has the same "identifier", now a UUID?
On 5/11/21 8:34 PM, Alec Habig wrote:
If you clone the whole thing using a lowlevel tool, say "dd": it will also clone the UUIDs. In your case, if you plan on removing the old disk before booting up with the new disk, that means it should just happily "wake up" in its new disk and never know the difference. On the other hand, if you're trying to clone partitions around onto new disks this way without pulling the old disk out (trying to expand your storage), then the duplicate UUIDs cause you trouble, because you'd have devices with the same UUID. You can generate new UUIDs if this is the case, by temporarily addressing things using hardware addresses instead. I've done this using similar disks (replacing failing drives) and it worked fine. But, I'm not sure if the differences in low-level geometry/blocksizes between different technology disks could cause a problem. I suppose it can't hurt to try: you can always reformat the new disk if it doesn't work.
