Yes, it is called Online Capacity Expansion.  You can reconfigure your 5-disk RAID 5 to include more disks by adding them to the array.  It is not-destructive and can be done while online.  You will need to use the Reconfigure function in the OpenManage software to do this, either by adding the VIB to ESX or booting to an OMSA Live disc. Once you have added the disks to the array, you will need to resize the appropriate partitions in ESX.  Also, I think that 5+ uses GPT by default, but keep in mind that if it does not, then your array will be limited by ESX to 2TB of usable space.  This would probably only (potentially) be a problem if you upgraded TO 5.x from some other version.
Hello, I've a PE R510 running VMWare ESX5 hypervisor (embedded) on mirrored SDs.  We've 5 x 146GB SAS disks currently in a RAID5 config which provides approx 1.6TB raw storage for the VMFS datastore. I'm trying to understand if it is possible to add additional disks to this RAID5, therefore expanding the Virtual Disk, without the need for destroying/loosing the data in place?  If so, what the steps would be to do this? Thanks, Chris
R510 PowerEdge - Expand RAID5 with additional disks