How can I migrate a RAID1 setup to larger drives on an LSI 3ware 9650SE?

Solution 1:

Yes, this is possible with most hardware RAID controllers. The overview of the steps needed for your controller are here.

You can replace each disk one at a time, allowing time for the drive to rebuild before moving to the next drive.

Once the array is built with the newer, larger disks, you will be able to leverage the additional space at the ESXi level. You can either use it to expand the existing datastore or create a new datastore.

Are you just looking for more space in general, or more space for the existing virtual machines?

Also see:

Does any hardware RAID controller support hot expanding a unit to larger disks?
and
What are the recognized ways to increase the size of the RAID array online/offline?