Nearly four years on the QNAP TS639 Pro I referred to a few posts earlier in the thread has continued to give trouble-free service. QNAP have also been active over the years, even once the product was superseded, with firmware updates. I initially populated the box with 4 x 1.5TB drives (1TB = a million million bytes) giving a RAID 5 capacity of 4TB. RAID 5 offers fault tolerance - a drive can fail without loss of any data. I never thought I'd need more but, in the best Dickensian tradition, more was called for! I could have added a further two 1.5TB drives but with the originals being regular, rather than enterprise, grade drives and four years old to boot I decided to bite the bullet and buy 4 x 3TB drives plus a spare, this time opting for drives rated for 24/7 usage.
The upgrade required me to hot swap the four drives, one at a time, allowing the RAID 5 array to rebuild between swaps. That took eight hours per drive during which time I was a little nervous as a drive failure during the day and a half or so that the whole procedure took would have meant me digging out my off-line backups and starting from scratch. With the four new drives in place the NAS capacity went from 4TB to, er, 4TB.
Actually, that was expected and the last stage was to instruct the NAS box to use the extra capacity. That was another slightly scary moment as the progress indicator started at 25% and then took about an hour to get to 28% at which point I went to bed. Happily things speeded up overnight and I now have the full 8TB available, all the original bytes being preserved.
I think this is a win for having a dedicated NAS box. My choice was to go for a commercial option rather than a self-build but however you slice it the opportunity to perform a significant capacity upgrade with all the original data intact is very handy. I'm not even sure 3TB drives were available when I bought the NAS and even if they were they would have been totally unaffordable. I could have opted for 4TB drives this time around but cost wise they didn't make sense, especially as I still retain the option to add another couple of 3TB units to the two spare drive bays.
Bottom line: don't be put off by the high initial price of a Network Attached Storage device. Get a good one and you'll get a level of ongoing support that seems rare these days and you can refresh it in a few years time as and when larger hard disks become available at affordable prices. Update:
And rather than throw away those 1.5TB drives I've just ordered a QNAP TS-412
to put them in. It's a bargain basement unit and I can use it as an off-line (normally unpowered as those disk drives are getting on a bit) back up for my data with the disk drives configured as JBOD (Just a Bunch of Disks) for the best part of 6TB of peace of mind. Recycling rocks.