Alignment of the VMFS partition on i5 storage spaces

Answer

Below are steps to create an aligned VMFS partition on a 'User-defined' i5 storage space.
1. On the System i Navigator interface, expand Integrated Servers Administration → Servers
2. Expand the plus sign next to one of the ESX servers linked to the new storage space. Click on Linked Virtual Disks.
3. On the right pane, look for the new storage space. Take note of the Sequence Position number next to the storage space name.
4. Open a session on the ESX server service console as root.
5. Enter the esxcfg-vmhbadevs command to get the list of the disk drives:
# esxcfg-vmhbadevs
The command output is below.
vmhba1:0:0 /dev/sda
vmhba1:0:1 /dev/sdb
vmhba1:0:2 /dev/sdc
The 'vmhba1' is the iSCSI initiator HBA where '1' is the host number.
The second number is the Target number.  This will always be 0 for i5 storage spaces.
The third number is the Logical Unit Number (LUN). The LUN is the i5 storage Sequence Position, minus one. The 'user defined' storage will start at LUN 2.
6. Double check that you are going to format the right datastore. Enter the following command on the console. In this command, the number 2 is for LUN 2.
# grep Model /proc/vmware/scsi/vmhba1/0\:2
which will have the following output.
Vendor: IBM Model: VDASD VMWAPP03 Rev: 0001
Note: i5/OS virtual disks will have Vendor 'IBM' and Model 'VDASD XXXXXXX' where the 'XXXXXXX' is the name of the i5 storage space.
7. Now you are sure that /dev/sdc is the right disk drive to be formatted. Start the fdisk utility,
entering the command:
# fdisk /dev/sdc
8. On the fdisk steps, make the following choices:

a. Command (m for help): type n for new partition
b. Command action: type p for primary partition
c. Partition number: type 1
d. First cylinder: press Enter to accept the default
e. Last cylinder: press Enter to accept the default
f. Command (m for help): type t to set the partition’s system ID
g. Hex code: type fb to set the partition system ID to fb (VMware VMFS volume)
h. Command (m for help): type x to go int expert mode
i. Expert command: type b to adjust the starting block number
j. Partition number: type 1 to choose partition 1
k. New beginning of data: type 63 to set it to 63
l. Expert command: type w to write label and partition information to disk

The 'datastorename' is the name of the datastore you are creating which have the same name as the storage space.
The 'vmhba1\:0\:2\:1' description:
The 'vmhba1' is the iSCSI initiator HBA associated with LUN 2 from step 5.
The second number '0' is target associated with LUN2 from step 5.
The third number '2' is the LUN number.
The forth number '1' is the partition number of the VMFS partition. We recommend 1 partition per 'user defined' storage space, so this number will always be 1.