Performance

Tests were run with 1.24 firmware using our standard test process and Figure 7 presents a summary of the benchmark tests run with a Gigabit LAN connection. Cache boost at lower file sizes is moderate, but performance falls off considerably at file sizes 256 MB and higher. Read speeds also fall off, but not as much as write.

Figure 7: Performance Benchmark summary

RAID 1 Write performance with a 1000 Mbps LAN connection averaged over the 32 MB to 4 GB file sizes and with cached results above 125 MB/s removed from the average measured 38.8 MB/s with read speed somewhat slower at 27.5 MB/s. But a look at Figure 7 shows the higher write average is due to caching effects at smaller file sizes. Once cache effects disappear at 512 MB file sizes and higher, read speed runs around 25 MB/s while write is about 10 MB/s lower at 16 MB/s.

While these aren't terrible results, they rank the Link Duo toward the bottom of the charts for two-bay recent-generation NASes.

RAID 1 file copy write performance of 19.1 MB/s using our Vista SP1-based test was about in line with non-cached write speeds shown in the iozone-based tests above. Figure 8 shows that the Link Duo was similar to other recent Kirkwood NASes like the Seagate BlackArmor NAS 220 and Iomega ix2-200. But it's a good 10 MB/s slower than its TeraStation Duo sibling, which uses a beefier Marvell MV78100-A0 C080 single core ARM processor.

Figure 8: RAID 1 Filecopy write ranking

The Link Duo slips lower, however, in the RAID 1 read file copy rankings, hovering just above the Linksys Media Hub and Thecus N2200 at 25.8 MB/s.

Backup

I checked backup performance to an Iomega UltraMax Pro Desktop Hard Drive configured in RAID 0 attached to the Duo's USB 2.0 port. The test copies the 4.35 GB ripped DVD test folder that I use in the NAS Chart Vista SP1 file copy tests from the NAS to the attached drive. The results are summarized in Table 1.

Table 1: Backup throughput test summary

The good news is that at least you get a backup feature. The bad is that you'll wait a long time for it to finish! Given the limited network backup support, Buffalo should have done a better job on attached backup performance.

Closing Thoughts

I would have liked to see Buffalo go for higher performance in the LinkStation Duo. But I suspect that the Duo is more of a price than a performance play. At a bit over $200, which includes two 500 GB drives, it seems to be aiming for the same buyer that might go for a NETGEAR Stora. But between the two, the LinkStation Duo will appeal more to buyers looking for an inexpensive RAID 1 NAS with decent performance and more "traditional" NAS feature set.