Ok, answering my own question

I reformated it this way:

/var/log # vmkfstools -C vmfs5 /dev/disks/naa.50002ac002c30dab\:2
VMFS5 file system creation is deprecated on a BIOS/MBR partition on device 'naa.50002ac002c30dab:2'
Checking if remote hosts are using this device as a valid file system. This may take a few seconds...
Creating vmfs5 file system on "naa.50002ac002c30dab:2" with blockSize 1048576 and volume label "none".
Successfully created new volume: 4f75271e-63939b80-ddcc-e4115beb3630