Here is a situation that has come up now I think four times when I have been installing ESX or ESXi, the second drive I put in usually for the Guests and it is going to be formatted by ESX or ESXi, it cannot be seen until I reboot and use Gparted, then it seems like it is better to have it formatted in NTFS or FAT32 rather than Linux native extfs for some reason.
I keep Gparted with me all the time, not just because of VMWARE, I have used it successfully for getting disks that have been wiped by dban, or need to be repartitioned without losing data, and to just plain fix disks gone haywire.
Great free tool. If you don't have it, get it. Get it here.