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Asked: 2013-05-08 02:06:59 +0800 CST

Are disk partition labels or UUIDS stored in the partition area itself or in some other area of the hard disk? [duplicate]

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Are disk partition labels or UUIDS stored in the partition area itself or in some other area of the hard disk?

e.g If the dd command is used is used to copy the raw partition image from one partition to another, or even onto a different hard disk. or the tar command is used (if it is stored in some special file) will the new partition have the same UUID or label?

Are they stored in some special area of the original physical disk or in the partition itself?

partition

1 Answers

  1. Both the label and the UUID are part of the file system, not the partition or something inherent to the disk.

    The question I linked to and that you deemed not helpful, explained that the UUID is stored in the superblock, which is a part of the file system and fully contained within the partition.

    So, if you do a dd if=/dev/sda1 of=/dev/sdb1, both sda1 and sdb1 will have the same label and UUID.

    Edit: More details.

    1. Google exist and it can tell you what a superblock is. This site is for professionals and I expect you to be able to get that kind of information yourself.

    2. An UUID is quasi-guaranteed to be unique at creation time. There is no explicit or implicit guarantee that it stays unique if it applied to an object and that object is cloned (as it is the case with a dd'ed file system. To make it explicit: If you clone a file system, the UUID will not be unique anymore as it is a part of the cloned filesystem.

    3. A MAC can't be considered unique for a long time now. You can change a MAC at will in many/most cases. The same is true with any aspect of a virtual machine.

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