[CentOS] Two partitions with samd UUID??

[Robert Nichols]

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/.

-- 
Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.