I'm looking for a NAS device for the purpose of running backups of several other machines. My current setup for this is a consumer PC with extra drives plugged in, but this is non-optimal for several reasons.
I want NAS hardware because consumer PC hardware with enough disk slots usually comes in an enormous case and requires expensive motherboards and so forth. This system does not need high hardware performance, and ideally would cost less than $500. However, I intend to install a standard Linux distribution on it (probably Arch) and handle all software requirements myself. Thus, I need a system on which it is easy to boot from a CD or USB and install a new OS. (My prior research suggests that many NASs require fiddling with the hardware to achieve this; I'd prefer to avoid that.)
I would like at least four disk slots, and would prefer that it came diskless. I will connect it via Ethernet, and do not require any other network hardware. As mentioned above, it will be used only for periodic backups of other machines, which have live data; thus, the hardware performance other than network and disk bandwidth is mostly immaterial. And of course, because I will handle the software myself, I do not care about what software package it comes with, only that I can get rid of it.
Edit: The usual OS install process requires a video output, which is apparently rare on NAS hardware; however, it should also be possible to install over the network (particularly a distribution such as Arch whose install procedure is from the command line itself). Thus, while it would be more difficult, a device without video whose bootloader can be edited or replaced would also suffice, so long as an unrestricted network shell is available from the original OS.