RAID 5 NAS Performance
So, how good is the DIY RAID 5 NAS? Figures 24 through 27 compare the performance of the DIY RAID 5 NAS to Buffalo Technology's 1 TB TeraStation NAS. The same iozone procedure was used to take all of the data shown, but I ran iozone on a Windows XP Pro, 2.4 GHz Celeron P4, 1 GB RAM machine. So while the results aren't exactly apples-to-apples, the test machines used are close enough in configuration to allow a reasonably accurate comparison.
Figure 24: Write Performance w/ 100 Mbps LAN (click to enlarge)
Figure 25: Read Performance w/ 100 Mbps LAN (click to enlarge)
Figure 26: Write Performance w/ 1000 Mbps LAN (click to enlarge)
From the benchmark results, it is clear that if you are going to build your own NAS, you want to build it with a gigabit Ethernet card. On smaller file sizes, the gigabit-equipped DIY RAID 5 NAS is clearly superior on both writes and reads. But on very large files, it is slower than the TeraStation.
Figure 27: Read Performance w/ 1000 Mbps LAN (click to enlarge)
This behavior holds up regardless of operating system used on the DIY NAS. Just for fun, I installed Free NAS .671 to compare with the Ubuntu results. Averages tend to hide things, but I've computed the average read and write speeds for the TeraStation and the DIY RAID 5 NAS using Ubuntu and FreeNAS .671 and summarized the results in Table 2. The read and write results represent the average of 32, 64, 128, 256, 512 and 1024 MB file size runs using 64 kB record size.
The averaged results show that the DIY server using Ubuntu comes out a little faster with a 100 Mbps connection, but blows away the Terastation with a gigabit Ethernet connection - even without using Jumbo frames! Since a gigabit Ethernet NIC costs less than $20, its inclusion in any DIY NAS is a no-brainer.
|TeraStation NAS 1.0 TB||DIY RAID 5 NAS|
|Ubuntu 6.06 DT||FreeNAS .671|