Expanding an Ultra 4 8TB -> ???

nsne wrote:
1. What is the Ultra 4's max internal storage capacity? Is it indeed 16TB?

The largest commonly-available drives are 4TB, so yes. 4x4TB = 16TB. If you're using RAID5 (single-drive redundancy), your usable space will be 12TB.

However... There's an unfortunate expansion limit at 8TB above the initial size of your usable array. So if you originally started with two 2TB drives, for example, your initial usable array size would have been 2TB and the largest usable array to which you can automatically expand will be 10TB (e.g. 4x3TB, or 2x3TB + 2x4TB, or 2TB + 3x4TB). If you started with your current setup (4x2TB, for 6TB usable space), you're safe: You can expand all the way to 4x4TB without hitting the expansion limit.

nsne wrote:
2. Can I begin adding higher-capacity HDDs (e.g., 4TB or 3TB) by simply hot swapping them for the existing 2TB HDDs to see an immediate and corresponding increase in storage capacity?

Yes. Launch Frontview, pull one drive from the NAS, remove it from its tray and attach a new 4TB drive in its place while you wait for Frontview to pop up an alert that a drive has been removed, then insert the tray with the new 4TB drive and watch it resync in Frontview. When it's done, it'll probably tell you to reboot.

If you have more drives to replace, do them one at a time as above. Note that if you are running in RAID5, you won't see any storage increase until you replace at least two drives.