The default firmware already has a few plugin modules that enhance its features. I’ve described them above. You can also install new plugins by downloading them on the appropriate page of the NAS's web-interface. You can manage plugins by enabling, disabling and removing them. Plugins can integrate into the NAS’s web-interface if necessary.
As a matter of fact, the manufacturer only offers to download one plugin that implements a Squeezebox server for audio streaming. It is managed via its exclusive web-interface on port 9000. However, the currently available combination of the firmware and plugin are not compatible: the plugin cannot connect to the integrated MySQL server.
There are a number of forums on the Web where users try to build their own plugins for this NAS but I didn’t find anything particularly useful there.
You can also get a console access to the root file system but the NAS’s processor isn’t very popular and further actions won’t be trivial for you unless you’ve got some solid Linux experience.
I benchmarked the performance of the Javelin S4 with Intel NASPT using Western Digital Caviar Black WD5001AALS disks with capacity of 500 gigabytes. I created a disk volume, a shared folder and a user account. Otherwise, I didn’t change any default settings. The NAS turned out to be unstable with Jumbo Frames turned on, so I didn't use that technology.
The Javelin S4 is average in performance. Its top read speed is 80 to 90 MB/s, which is quite close to the theoretical bandwidth of a Gigabyte Ethernet connection. The speed of writing is lower at 55 to 65 MB/s. It’s clear that RAID5 is quite a heavy load for the NAS's processor as this array has the lowest write speed in the test.
The Javelin S4 is a well-made product that features a nice exterior design and a robust chassis. With four disk bays, it can be used for both home and office applications. It's got a fast processor, a sufficient amount of system memory and USB and eSATA ports. Its read speed is close to the Gigabit Ethernet bandwidth but its write speed is only half as high. This performance is going to be sufficient for undemanding users, though.
I guess the least polished-off component of the Javelin S4 is its firmware and, unfortunately, Patriot can hardly do anything about it because they have to rely on the original manufacturer of this product. Although the firmware provides all the basic NAS features such as creating disk volumes, sharing files, accessing files via multiple protocols, managing users, etc, the extra functions that might be useful for home users are not implemented properly. Hopefully, enthusiasts will be able to enhance this product's firmware with their own hands.
What makes the Javelin S4 somewhat more interesting is that its price is rather low for a four-disk NAS. So, you may want to consider it if you need a high-capacity NAS for simple file sharing.