I assume the expected result was a size of 3gb on both datastores ?
If yes then there are 2 easy explanations:
- something along the process of creating the raid1 in Linux wiped one drive with zeroes while not doing that for the other one.
- the larger version was created as thick provisioned in the first place
Today I finally found, where is the problem. After instalation linux raid utility start disk synchronization and synchronize disk based on bitmap policy. So it synchronize whole space of disk even if is unused and fill unused space with zeroes. But for vmware it means, that space is alocated.