How to extend the virtual disk size in ESX/VM

1. Power off the VM-1
2. Make clone of this VM -1 , call it VM-2 (for backup , in case you mess with VM-1)
3. From Vsphere client , increase the size of the VM-1 , you can also increase with a command line tool. #vmkfstools -X 40G VM-1.vmdk (-X is the switch for the size that you want the disk file to be , not the size you want to extend).
4. Power down VM-2
5. On Hardware tab add a new existing HDD and point it to the original VM-1.vmdk (the disk we resized few minutes back), mount it as second HDD.
6. Boot VM-2
7. From run menu type “diskpart”, this utility resize disk partition in windows 2k3
8. DISKPART> list volume , will show you the list volume , select your volume that you want to extend.
9. DISKPAER> extend , run this command to finally to extend the HDD size.
10. You can cross check the HDD size in HDD management snapin (mycomputer->manage->Disk Management)
11. Shut down VM-2 and remove the disk we added
12. Power on the VM-1
13. Voila you are back to business

another way of doing this

1. Power off VM
2. Add a blank larger target disk
3. Add a temp disk (formatted NTFS) to hold a ghost or acronis image
4. Boot to Ghost or Acronis CD
5. Image source disk to image on your temp disk
6. Restore temp image to your larger disk
7. dismount your source and temp disks and test a boot
8. If everything goes well then you are done, you can delete your temp and source disks.
9. if something bad happen then you can revert back to your original disk.