I used to build my own file servers but 2-3 years ago I bought a ReadyNAS ProBusiness at home and I love it. Granted it cost me about $1500 at the time, but it has made my life so much easier. I'm at the stage of my life where I'd rather pay extra and save time.
It supports almost everything out of the box, and there's very little configuration. It has 6 hot-swappable bays, and it allows for automatic expansion using their proprietary system, X-RAID 2. I currently have 4 500 GB drives, and 2 1 TB drives, and if I want to expand it, I just buy another 1 TB drive and swap out a 500 GB drive.
It also supports streaming protocols, including ReadyDLNA so I can play movies directly off my PS3. It also seamless supports TimeMachine for my Mac laptops. I really do love this thing.
i got a pro recently to share/backup a dropbox share over a network. The sharing, raid and backup stuff is all standard with the linux based os which makes it nice and easy. the pro readynas boxes are also intel atom cpu so its simple to stick the linux dropbox client on it.
This HP box looks much better value than the readynas though, as long as you want to install the OS/raid etc yourself.
I love my ReadyNAS. I got a NV (not NV+) from back in 2005 that is still going strong. And they have issued regular updates (last release was earlier this year). So the price premium that you pay over a QNAP or Synology is worth it IMO.
That said, there are some cons too. In my limited testing, ReadyNAS is not the fastest device out there so if you are looking the absolute fastest, they are probably not it.
The older Sparc based NAS devices do not get as much firmware love as the newer ones. So probably no IPv6 and GPT. Also, the older devices support only ext3 not ext4.
I found out last year that my particular NAS was due for a recall on the power supply. Unfortunately, this recall had been issued several years earlier and I just had not noticed it. TL:DR, ReadyNAS replaced it gratis even though the recall notice had expired several years prior.
Other than what I listed above, I can wholeheartedly recommend the ReadyNAS. Remember, this is your data we are talking about and it is sufficiently important to me that I'm okay spending a bit more money to make sure it is well protected.
Not sure about the ReadyNAS ProBusiness, but my NV+ has a USB port that I can plug an external drive in to, push the backup button, and in just a little bit I'll have a drive suitable for taking off-site. The FrontView web interface has a simple way to configure what the backup button does. Very simple.
It also runs Linux under the hood, and I've been able to configure CrashPlan for off-site backups of some key files too.
I use the USB port as well and connect a USB drive to it. But I am a bit more paranoid, and I do a bit-by-bit comparison of every file that I copy, after I do the backup.
It supports almost everything out of the box, and there's very little configuration. It has 6 hot-swappable bays, and it allows for automatic expansion using their proprietary system, X-RAID 2. I currently have 4 500 GB drives, and 2 1 TB drives, and if I want to expand it, I just buy another 1 TB drive and swap out a 500 GB drive.
It also supports streaming protocols, including ReadyDLNA so I can play movies directly off my PS3. It also seamless supports TimeMachine for my Mac laptops. I really do love this thing.