RAID expansion question

StGeorge wrote:
I'm just curious if adding 2X500Gb drives helps when you have 3X1TB in RAID.

If you were adding 1TB or larger drives, they would just automatically increase the size of your array without affecting your existing data, while the NAS remained online and accessible. You cannot do that automatic expansion using the 500GB drives, though, because they are smaller than the largest drive in your Pro6. To use the 500GB drives, you'd have to backup all your data from the Pro6, install the new drives, factory-default (i.e., reformat) the Pro6, then restore your data.

Your Pro6 currently has a 2TB array (which is probably displayed in Frontview and Windows as something like 1832GB, but that's just because drive manufacturers use a different definition of "TB" than everyone else). If you inserted the two 500GB drives and did the whole backup-format-restore procedure, you'd end up with a 3TB array.

If that sounds like a lot of work for a 1TB storage increase [it does to me, especially since 1TB drives can be had for around $50 with free shipping], but you don't want to discard the 500GB drives, perhaps you could put them in USB enclosures and use them for external storage or local backups or something.