I have used dd command to clone disk A to disk B. However, in some cases (not always), after a successful clone, fdisk on disk B gives me:

GPT PMBR size mismatch (937703087 != 1000215215) will be corrected by w(rite).

I know the question was asked here before: GPT PMBR size mismatch after dd clone

My question is why this error occurs sometimes but sometimes not. My own experience is that when the disk A and B have different physical sector sizes, this error happens. But it could be a mis-impression. Or maybe some disks do not have a secondary backup GPT and this error only happens with those disks with a backup GPT? Can someone shed light on this please?

As always, thanks!


You can always do:

sudo parted -l

The error happens when for example:

Disk A is 100GB;
Disk B is 1TB;

When you DD, you "clone" the same, and it misleads Ubuntu, into believing that the (now clone of a disk) is 100GB.

When you do the aforementioned command, it "resets" this.

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