You can use any existing free space on your VMFS volumes to create new disk partitions.
If a core dump file does not exist on the disk, you are offered to create one. Creating a new volume consumes all the free space remaining on a disk. ESX Server determines the optimum setting for the maximum file size based on the volume's file system.
Caution: Do not place your core dump partition on a SAN disk. If the SAN cable is removed, ESX Server becomes unstable.
To create a new partition, complete the following steps.
If you need to create one or more partitions with specific properties, click Custom.
If it does not exist, you are asked if you want to create a core dump partition.
The core dump partition stores information generated if the VMkernel crashes. The core dump information is important in debugging any problems with the VMkernel.
The rest of the disk or array is used as a VMFS partition, where you store virtual machine disk files. The VMFS partition provides high-performance access to the virtual machine's files - essentially the same performance you would get if the virtual machine were installed on a raw SCSI partition.
Note: Keep in mind that only four primary partitions can exist on a drive. If you have an extended partition (to contain logical partitions), that counts as one of your four primary partitions.
After you create the partition, you can add a volume label, determine access mode and the maximum file size and span the disk with any public extents.