As you can see, we use a pretty strong test system with an ultra-fast OCZ Vertex 4 SSD installed. All tests are executed off the SSD to ensure that there is no bottleneck on its side since this specific SSD can achieve up to 560 MB/s read and 510 MB/s write speed (sequential).
NAS Configuration
Internal Disks:
2x Seagate ST500DM005 500 GB (HD502HJ, Serial ATA III, 7200 RPM, 16 MB)
External Disks:
Seagate Barracuda ST350063 in USB 3.0 enclosure
Firmware:
DSM 4.1 - 2650
Ethernet Switch:
TL-SG3216 16-port Gigabit managed switch (LACP and Jumbo frames support)
Ethernet Cabling:
CAT 6e, 2 m
Methodology
We use three different programs to evaluate the performance of the NAS. The first is Intel's NAS Performance Toolkit. Intel was kind enough to build a NAS performance toolkit. Not only did they release it for free to the public, but they also provided its source code. The only problem with this toolkit is that the results of two tests ("HD Video Record" and "File Copy to NAS") are heavily affected if you use a client PC with more than 2 GB of memory because they measure the client's RAM buffer speed and not the network speed, which is why we set the maximum memory in our test PC to 2GB via msconfig's advanced options. We exploit its batch-run function, which repeats the selected tests five times, during all tests with this toolkit and use the average as the final result.
The second program is a custom-made program that performs ten basic file-transfer tests and measures the average MB/s speed for each transfer. We run all selected tests ten times and use the average as our final result to ensure results are as accurate as possible.
The third program we use in our test sessions is ATTO, a well-known program for storage benchmarks. In order to use ATTO for benchmarking, we are forced to map a shared folder of the NAS to a local drive because ATTO cannot access network devices directly.