difference between RNDP 6620 & 6630

There is nothing locked down in the OS, the different model numbers just reflect the number and size of the disks the unit is shipped with. A 6000 has the same capacity, and comes with no disks at all.

There are 2 limits to on-line expansion. Both relate to the delivered volume size (not including the redundancy tax). One is that a volume cannot grow more than 8 TiB over its lifetime. The second is that the volume cannot grow across the 16 TiB boundary.

In your case, if you are running single-redundancy your installed volume should have been "born" at about 10 TB, so it can grow up to 16 TiB. upgrading to 6x3TB would leave at at about 15 TB, so you wouldn't run into either growth limit.

Before expanding, you should have an up to date backup, since there is always risk of data loss when you are rebuilding your raid array. (Really you should always have a backup...)

You can hot-swap the disks one at a time (waiting for resync to complete before you insert the next one). You might need to restart the NAS after the initial resync, particularly after the second disk insertion (which would be the first one which increases the volume size). When I insert a 3 TB drive, it takes my pro-6 about 10-12 hours to complete the process. So it would take about a week. The data would be available, but performance would be slowed down.

The other option is to power down, pull all the disks (labeling their slot), insert the new drives and power up. Then restore the config and the data. The NAS will be unavailable for a while, but the total process will be quicker, and you end up with a clean setup.

Another thing you should note is that you need to update to RAIDiator-x86 4.2.16 (or later) if you haven't already before adding 3TB disks.

just checked: still running raidiator 4.2.15. Went to the website to download the latest version and came across this sentence: "Volume expansion will not work beyond 16 TB. To support 16 TB or greater, you’ll have to factory default with that capacity in place."

Does this imply that I have to back up everything, install the 3TB harddisks, factory default the NAS and then install the data again!!!

Please advise!!! thanks

Have a read of Stephen's post above. He explained the two expansion limits.

ok! think i got it now! the key is the volume size! Missed that at 1st reading. THANKS!