Need to add a disk to an ESXi 5x server and format as VMFS? Here is how you do it from the ESXi CLI. Enable ssh on the ESXi host in vCenter and login as root via xterm or putty. This was done on an HP DL360.

1) Find your disks.

> ls /vmfs/devices/disks/
-or
> esxcfg-scsidevs -c

The new disk is: mpx.vmhba1:C0:T1:L0

2) Create a partition.

> fdisk /vmfs/devices/disks/mpx.vmhba1:C0:T1:L0
Select: m
Select: l
Command (m for help): n
Command action
e   extended
p   primary partition (1-4)
Select: p
Partition number (1-4): 1
First cylinder (1-8920, default 1): Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-8920, default 8920): Using default value 8920

Command (m for help): p

Disk /vmfs/devices/disks/mpx.vmhba1:C0:T1:L0: 73.3 GB, 73372631040 bytes
255 heads, 63 sectors/track, 8920 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot      Start         End      Blocks  Id System
/vmfs/devices/disks/mpx.vmhba1:C0:T1:L0p1             1      8920  71649868+  83  Linux

Command (m for help): w
The partition table has been altered!

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): l

0 Empty                             1c Hidden W95 FAT32 (LBA)     a5 FreeBSD
1 FAT12                              1e Hidden W95 FAT16 (LBA)     a6 OpenBSD
4 FAT16 <32M                 3c Part.Magic recovery                 a8 Darwin UFS
5 Extended                        41 PPC PReP Boot                         a9 NetBSD
6 FAT16                              42 SFS                                             ab Darwin boot
7 HPFS/NTFS                   63 GNU HURD or SysV               b7 BSDI fs
a OS/2 Boot Manager      80 Old Minix                                 b8 BSDI swap
b Win95 FAT32                 81 Minix / old Linux                    be Solaris boot
c Win95 FAT32 (LBA)      82 Linux swap                              eb BeOS fs
e Win95 FAT16 (LBA)      83 Linux                                         ee EFI GPT
f Win95 Ext’d (LBA)         84 OS/2 hidden C: drive             ef EFI (FAT-12/16/32)
11 Hidden FAT12                85 Linux extended                        f0 Linux/PA-RISC boot
12 Compaq diagnostics      86 NTFS volume set                    f2 DOS secondary
14 Hidden FAT16 <32M    87 NTFS volume set                    fd Linux raid autodetect
16 Hidden FAT16                8e Linux LVM                               fb VMFS
17 Hidden HPFS/NTFS     9f BSD/OS                                     fc VMKcore
1b Hidden Win95 FAT32   a0 Thinkpad hibernation

Hex code (type L to list codes): fb
Changed system type of partition 1 to fb (VMFS)

Command (m for help): w
The partition table has been altered!

3) Create the filesystem.

> vmkfstools -C vmfs5 -b 1m -S <new datastore name here> /vmfs/devices/disks/mpx.vmhba1:C0:T1:L0:1

VMFS5 file system creation is deprecated on a BIOS/MBR partition on device ‘mpx.vmhba1:C0:T1:L0:1’
Checking if remote hosts are using this device as a valid file system. This may take a few seconds…
Creating vmfs5 file system on “mpx.vmhba1:C0:T1:L0:1” with blockSize 1048576 and volume label “Datastore name”.
Successfully created new volume: 512bee4b-d5bd5128-568e-0015174b0172

4) Done.