To test the DS-101's performance for networked data reading and writing , I used the iozone tool described on this page. In my specific case, the iozone test was running under OS X on my iBook which has 640 MB of RAM. The disk I installed in the DS-100 was a Maxtor 120 GB, 7200 RPM drive with 8 MB cache and not supplied by Synology.
File system performance, i.e. how fast your computer can read / write data to a drive, depends on many factors that are specific to the system running the test. So to put the results in perspective, I also ran the same iozone tests against a Linksys NSLU2 and a Buffalo Technology Kuro Box using the same parameters and network connections. I didn't use the same hard-drive on the boxes, however, so the tests are not exactly apples-to-apples comparable. But the results should provide some idea of relative performance.
Figures 5 and 6 show DS-101 transfer rate over varying file and record sizes for read and write respectively. Note that the zero-value areas at the left-front and right-rear of the graph are file and record sizes that weren't tested. Both show performance between 5,000 and 7,000 kBytes/sec.
But, like I said, since performance is so system (including OS) dependent, a comparative look at the three NAS devices I tested is more informative. Figure 7 shows the DS-101, Kuro Box and NSLU2 / Maxtor USB write performance for a 128 MB file size over varying record sizes. The DS-101 edges out the other two devices, but remember that the same hard drive isn't used in all devices.
Figure 8 provides the read test comparison, which shows the Kuro Box besting the DS-101.
I think the only safe conclusion is that both the DS-101 and Kuro Box provide better performance than the NSLU2 / Maxtor combination - which I'd attribute to the IDE vs. USB2.0 drive connection.