Are LUN serials kept in separate location from LUN itself?

[aborzenkov]

I noticed the following in Block Management Guide (Mapping read-only LUNs to hosts at SnapMirror destinations):

The destination LUN is also assigned a new serial number.

I always thought that LUN serial is LUN property kept together with LUN itself. But then how can it be changed on fundamentally read-only destination? Or is it kept in some external global location?

[scottgelb]

After head swaps (sometimes) I have seen them change too so we check after every head swap now.