[lug] Identical UUID for MD devices?

[Rob Nagler]

On Thu, Feb 8, 2018 at 12:46 PM, stimits <stimits at comcast.net> wrote:

> When I had to replace a windows disk and didn't want to mess with
> reactivating everything (it was the same computer, just the disk being
> replaced) I used Linux to copy from that disk to another of the same exact
> model. I used dd. This left the UUID as an exact clone, whereas running
> something like mkfs.ntfs would cause a change. The UUID is just part of the
> file system like any other data. If the mirror operating was done by raw
> byte copy I'd expect UUIDs to be a clone.
>

Each device layer has its own UUID: disk (sdX), raid (mdX), crypt pv
(/dev/mapper/luks-*), vg (/dev/mapper/foo-bar), etc.

BTW, it seems that crypt volumes have a different style of UUID: more
characters and base62. The UUIDs are strings, not numbers. Pretty
interesting.

Rob
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