To enable an operating system to uniquely identify disks, a signature is generated as part of the initialization initialisation process. In the case of an MBR partitioned disk, this is a 4 byte value, typically presented as an 8 character hex string. This is extended to a 16 byte value for gpt disks, presented as a GUID.
You can see the disk signature by opening a command window, and typing
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diskpart |
followed by
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list disk sel disk <n> |
replacing <n> with the number of the disk you wish to query and then type
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detail disk |
MBR disk example
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DISKPART> detail disk ... Disk ID: 4936F9A1 |
...
GPT disk example
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DISKPART> detail disk
...
Disk ID: {C0F4976C-CFA6-45C1-BBCE-3B40016336E5}
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...
Unlike MBR partitions, GPT partition entries have an associated unique id. This allows GPT partitions to be uniquely identified without the disk signature making the disk signature redundant for the purposes discussed above.
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| Note: Windows does not allow multiple disks to be online with the same MBR Disk ID or GPT GUID. For this reason, Macrium Reflect will always ensure there are no duplicates when restoring or cloning. |
Summary
The following table indicates how disk signatures are treated for restore or clone operations:
| Operation | Target disk Signature |
| Any restore or clone to a GPT disk | Not changed, or if target not initialized a new one is Existing signature is not changed. Or, if the target is an empty/uninitialised disk then a new random signature will be generated. |
| All target partitions overwritten | From The signature will be the same as the source disk for an image Restore operation. |
| Source disk id present after restore (e.g. in the case of a clone) | RegeneratedNew randomly generated signature |
| Some original target partitions remain after restore | Not Existing signature is not changed. |
| Target partitioning scheme different from source (e.g. source MBR, target GPT) | Not Existing signature is not changed, or ifIf the target not initialized a new one isis an empty/uninitialised disk then a new random signature will be generated. |
| Target uninitialized, MBR source disk, target < 2TB | From The signature will be the same as the source disk /in the image |