I have multiple hosts where we setup a 3GB volume on the SAN to install ESXi 4.1, which used up about 1GB for the install and then the rest was used for a vmfs for scratch.

After the upgrade to ESXi 5 it didn't mount that scratch vmfs.When trying to reformat it, I get an error:

     Either the selected disk already has a VMFS datastore or the host cannot perform a partition table conversion. Select another disk.

fdisk from the cli shows:

Disk /dev/disks/naa.50002ac002c30dab: 3221 MB, 3221225472 bytes
64 heads, 32 sectors/track, 3072 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes

                           Device Boot      Start         End      Blocks  Id System
/dev/disks/naa.50002ac002c30dabp1             5       900    917504    5  Extended
/dev/disks/naa.50002ac002c30dabp2           901      3072   2224128   fb  VMFS
/dev/disks/naa.50002ac002c30dabp4   *         1         4      4080    4  FAT16 <32M
/dev/disks/naa.50002ac002c30dabp5             5       254    255984    6  FAT16
/dev/disks/naa.50002ac002c30dabp6           255       504    255984    6  FAT16
/dev/disks/naa.50002ac002c30dabp7           505       614    112624   fc  VMKcore
/dev/disks/naa.50002ac002c30dabp8           615       900    292848    6  FAT16

So p2 is the 2.12GB vmfs. Is there anyway to get it mounted again? "esxcli storage vmfs snapshot list" does not list it as a snapshot.