On 06/15/2015 07:56 AM, Robert Nichols wrote:
On 06/14/2015 10:08 PM, jd1008 wrote:
On 06/14/2015 08:58 PM, John R Pierce wrote:
On 6/14/2015 6:55 PM, Timothy Murphy wrote:
Maybe I used dd at some point.
Would this keep the same UUID?
DD just does a blind block by block copy between two devices or files.
I thought that uuid had nothing to do with drive content,
so dd would have (should have had) nothing to do with it.
You thought wrong. The UUID for a GPT partition is a number that is
recorded in the GPT. The UUID for a filesystem is a number that is
recorded in the filesystem super block. The UUIDs for LVM physical
or logical volumes are numbers recorded in the LVM header. Etc.,
etc., etc. When you use dd to copy them, the UUIDs get copied
too, and significant confusion can result.
Now, the drive itself does have a UUID derived from information
that includes the serial number. But, unless you are referencing
the drive by /dev/disk/by-uuid/*, you are not making use of it.
I've occasionally used /dev/disk/by-id/xxx to select a particular
drive partition that could not be reliably identified in any other
way (encrypted swap partition on a non-GPT drive), but I don't
recall ever using /dev/disk/by-uuid/.
Thanx for the update
but what about non-gpt and non lvm partitions?
What is used as inp
nut to create a universally unique id?
(Actually, for an id to be universally unique, one would almost
nee knowledge of all existing id's.
So, I do not have much credence in this universal uniqueness.
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