It's possible to install any number of different hardware configurations in the Silverstone DS380, so these benchmark figures are just a rough guide. For testing, we placed four 7200RPM drives in RAID and tested with both FreeNAS (ZFS) and Windows (NTSF).
The best throughput results were achieved when using RAID5 in Windows. The read throughput pretty much maxed out the Gigabit Ethernet connection while the write performance was also very strong at 71MB/s. This made our custom NAS server pretty sprightly compared to expensive pre-built models such as the Synology DS1513+ and Thecus N6850.
The random 512K performance wasn't as impressive though, as we were limited to around 60MB/s read and 40MB/s write -- fairly average.