1. We can present new LUNs to the hosts, create new datastores, and storage vmotion the VMs off the old LUNs.
2. We can expand the existing datastores (what we did in this scenerio).
Firstly, we have to grow the LUNs that the VMFS file system (ATM machine, ha!) is stored on. This is pretty staight forward for pool LUNs..but a bit more complex for RAID group LUNs. Should you wish to use RAID group LUN expansion..you can stripe or concatenate two LUNs together.
Striping:
Pro-Performance benefits of any additional spindles are shared by all data.
Con-Re-striping takes time...delayed availability of additional space.
Concatenation:
Pro-SIMPLE; additional capacity immediately available.
Con-No performance benefit to existing data.
Lucky for us...we have pool LUNs..so it's as simple as expanding the LUN by right-clicking, choosing expand, and selecting the NEW LUN size.
Once we've expanded the LUN size...we have to tell VMware to use this new space!
Lets go back to the vCenter web client or the sphere client. We need to do a rescan on the storage devices.
Now that we've done a rescan, right-click on the datastore that we expanded the LUN on, and choose properties.
If we click on increase, we'll see the fibre channel disk with the ACTUAL capacity of the LUN, versus the capacity of the datastore.
If we click next, we'll see the VMFS partition size (the amount of space we sized the datastore) as well as the free space that was made available by expanding the LUN!
Once you complete the process, you'll need to do a rescan on the hosts to verify the expansion.
But thats it! Pretty simple.
Additional notes:
If you're having issues expanding your datastore...we found that disabling storage filters may help!
