I used IOzone to check out the file system performance on the 408 (the full testing setup and methodology are described on this page). My test unit had the latest DSM 2.0-0722 firmware and it was equipped with four 500 GB Seagate ST3500320AS Barracuda 7200.11 drives (SATA 3Gb/s, 7200RPM, 32MB) supplied by Synology. I tested it in RAID 0 and 5 modes with 100 Mbps, 1000 Mbps and 1000 Mbps w/ 4k jumbo frame LAN connections.
Figure 2 summarizes the write performance benchmarks. (I have included a data table in the larger version of Figures 2 and 3, so you can better see the exact performance results.) A 100 Mbps LAN connection clearly limits the 408's performance, so it's more instructive to look at the 1000 Mbps LAN tests.
RAID 5 imposes a throughput penalty, which is only slightly reduced by using a 4k jumbo frame connection. The best write performance is in RAID 0 with 4k jumbo frames, which comes in at 42.4 MB/s averaged across results for file sizes from 32 MB to 1 GB. Keep in mind that the 408's RAM is 512 MB. So it looks like Synology has tuned performance so that caching effects are greatly reduced from what we normally see.
Figure 2: DS408 Write Benchmarks
Read performance (Figure 3) is much more tightly clustered, but with less help from turning on jumbo frames. RAID 0 once again wins out, with a 49.3 MB/s large file size average for RAID 0 and 48.1 for RAID 5, which places the 408 at or near the top of the 1000 Mbps Read and 1000 RAID 5 Read charts.
Figure 3: DS408 Read Benchmarks
With this in mind, let's look at how the 408 stacks up against some competition, including the DS508 for good measure. After perusing the NAS charts a bit, I chose the Sans Digital MN4L+ (which hasn't had its full review yet) and the QNAP TS-509 Pro.
The 408's flat performance across file sizes is apparent in Figure 4. The Sans Digital is the winner for the RAID 0 write comparison with 48.3 MB/s averaged across the 32 MB to 1 GB file sizes. It's followed by the DS508 and TS-509 Pro virtually tied at 44.8 and 44.7 MB/s respectively, with the DS408 holding down the bottom of the ranking with 37.7 MB/s.
Figure 4: RAID 0 Write performance comparison - 1000 Mbps LAN connection
Raid 0 read (Figure 5) is a bit of a different story. The TS-509 Pro takes the top position in this chart with 51.4 MB/s, followed by the DS408 in the number 2 Chart position with 48.3 MB/s. The MN4L+ comes in third with 46.9 MB/s and the DS508 brings up the rear with 43.6 MB/s.
Figure 5: RAID 0 Read performance comparison - 1000 Mbps LAN connection
For RAID 5 write (Figure 6) the products average 46.2 MB/s for the MN4L+, 45.5 MB/s for the TS-509 Pro, 40.1 MB/s for the DS508 and 31.2 MB/s for the DS408.
Figure 6: RAID 5 Write performance comparison - 1000 Mbps LAN connection
For RAID 5 read (Figure 7) the averages are 54.2 MB/s for the TS-509 Pro, 48.1 for the DS408, 44.3 for the MN4L+ and 40.2 for the DS508.
Figure 7: RAID 5 Read performance comparison - 1000 Mbps LAN connection
Of course, you can run your own comparisons using the interactive NAS charts.