DM is death match. HM is a clothing brand (Hennes & Mauritz)

If you set it up to spin down the disk(s), you won't hear it. If you don't allow for disk spindown, it'll be annoying.

Since you don't intend to use any of its advanced functionality, I recommend that you go for something cheaper than DS224+. Like DS223 or DS223j

Don't leave us hanging! They're quite what?

When I started my first serious networking job, there was a syslog server in our datacentre that had been running nonstop for almost a decade. It was an ancient radiator-white supemicro 3u server with 6 SCSI disks. I decommissioned that server 7 years later. Those SCSI disks had been running nonstop for 16+ years without a single problem. The inside of the server was covered in black plastic dust from the slowly disintegrating case fans. Other than half the case fans not working, there was nothing wrong with that server.

Encrypted disk in my desk drawer at work. Contains everything apart from my movie collection. Many of my colleagues have now copied my approach.