8. Performance

100 Mbps Ethernet

Many readers find our 3D iozone plots confusing and uninformative, since caching effects from the computer doing the reading and writing tend to dominate the plot. After some experimentation and consultation with iozone's creator, Don Capps, we've decided to continue using iozone, but change the way we present the data.

According to Don, there are only a few record sizes that are of interest to most Windows applications: 4 K, 8 K and 64 K. 4 K is the memory page size, 8 K is one value that Windows appears to use for network transfers, and 64 K is the typical record size that Windows uses when applications try to transfer blocks of data that are bigger than 64 K.

So, starting now, we're going to show read and write performance plots using a record size of 64 kbytes, and transferred file sizes of 32, 64, 128, 512 and 1024 Mbytes. We think this will provide performance information that is easier to understand and more helpful for product comparison. We're also going to include a line on the plots that indicates the theoretical 12,500 kbytes/sec transfer rate of 100 Mbps Ethernet. If any product with a Gigabit Ethernet interface ever starts to approach Gigabit Ethernet speeds, we'll also include that line on the applicable plots.

So without further ado, here are the 100 Mbps performance results for both JBOD and RAID 1 modes. Thecus supplied the drives used in the 2100, which were Western Digital WD800JD Caviar SEs. These are 7200 RPM 300 Mbit/s SATA drives with 8 MB of cache.

Figure 11: 100 Mbps Ethernet read performance (click to enlarge)

JBOD and RAID1 read and write speeds show very little difference, and the slight speed advantage that read has disappears for file sizes 256 MB and above.

Figure 12: 100 Mbps Ethernet write performance (click to enlarge)