If a LUN belonging to an unmanaged Fibre Channel array is unmapped from a server and a new target is mapped to it using the same LUN, then after rescanning the physical disks on that server, the size of the new LUN is set to the size of the LUN that was unmapped.

Remapping LUNs is risky because it can data corruption since the targets have been switched outside of the server. An error should appear in the messages file:

Warning! Received an indication that the operating parameters on this
target have changed. The Linux SCSI layer does not automatically adjust 
these parameters.

Workaround: Ensure that when exposing a new target, you do so with a LUN that has not previously been used since the last reboot.

Bug 14851579