I tested the 320L with original (and latest) 1.0 firmware, using our NAS test process to run tests with RAID 0 and 1 volumes.
Windows File Copy tests in the Benchmark Summary below show read throughput 40% higher than write for RAID 0 (43 vs. 30 MB/s) and 60% higher for RAID 1 (38 vs. 24 MB/s).
Intel NASPT File Copy writes were 40% higher than Windows File Copy for RAID 0 (42 vs. 30 MB/s) and 54% higher for RAID 1 (37 vs. 24 MB/s).
There are no iSCSI results because the product doesn't support it.
Attached backup tests run via the single USB 2.0 port were pretty unimpressive. A FAT32 formatted volume yielded 15 MB/s and NTFS was much slower at 6 MB/s. Although network backup via rsync is supported, it poked along at 16 MB/s.
Performance - Comparative
To put the DNS-320L's performance in perspective, I ran a set of custom RAID 1 performance charts using the NAS Finder, filtered for Marvell Kirkwood-based, two-bay products. The first results show the Windows File copy benchmarks. Most of the products shown use 1.6 GHz 88F6282 Kirkwoods. But the QNAP TS-212 and D-Link DNS-325 use 1.2 GHz 88F6281 SoCs and still manage much better throughput than the 320L.
RAID 1 Windows File Copy Performance Comparison
The plot below shows the Intel NASPT File Copy results, which seem a bit kinder to the 320L. Still, it is clear that the 320L's strong suit is not performance. In real life use, I'd expect 25 - 30 MB/s RAID 1 writes during large file transfers and about 40 MB/s reads.
RAID 1 Intel NASPT File Copy Performance Comparison
Use the NAS Charts to further explore and compare the DNS-320L's performance
It's not that the DNS-320L is a bad NAS. But there are better options out there. For a bit more money, ZyXEL's NSA325 will get you as many features as you'd like, better performance and USB 3.0 port for much faster backups.