My old server is getting too slow, and I decided to separate the CIFS file server. There are a few open source NAS software available on the Internet. The most interesting ones are:
Anyway, along the search I found OpenMediaVault, which is based on Linux. Indeed, it is a package under Debian Linux. What I like about it is that it can use LVM (Linux Volume Manager), which can move data between different physical drives within a same volume group. With that, I can put a new larger drive into a group, move data onto it, and then remove the older drive. Another thing I really like about it is that it can be installed on many hardware platforms where Debian is available. For example, I have installed on x86/x64, Raspberry Pi (with Raspbian, need to follow these special instructions at this time 9/2014), and DreamPlug (with Debian and follow standard procedures).
At this time (September 2014), the installation method of the installation is quite straightforward. The standard procedure is rather straight forward. Now I am off testing it.