D-Link DNS-323 2-Bay Network Storage Enclosure ReviewNemo - January 1, 2009
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The Intel NAS Performance Toolkit is a set of tools used to test and analyze file systems and enable direct comparison of the performance levels of different network attached storage devices. It utilizes a set of tests based on real world applications such as HD video playback and record, office productivity, photo album manipulation and file and directory copying. The toolkit uses a set of traces based on these applications and mimics the file system traffic generated and records the system response. In our evaluation, the toolkit was run in batch mode which runs the series of tests five times in succession and the median throughput value used to report the results. The hard drives were reconfigured and the DNS-323 was rebooted before each test was run.
HD Video Playback (higher is better)
The HD Video Playback series of tests involve streaming a 720p HD video file using Windows Media Player and 256kb reads. The tests play either 1, 2 or 4 files simultaneously using different percentages of sequential reads (99.5% for the single file, 18.1% for the 2x HD Video Playback and 9.6% for the 4x HD Video Playback).
2x HD Video Playback (higher is better)
4x HD Video Playback (higher is better)
The DNS-323 really shines in the HD playback tests, turning in its highest performance numbers across all the tests. The playback tests are more dependent on raw data rate capability and managed to push data through at drive configurations ranging from around 19-22 MB/s in the single file test. We also see the biggest gains in throughput from both RAID 0 and enabling jumbo frames here. If streaming multimedia were to be the main use, the DNS-323 would be more than capable of achieving acceptable data rates.
HD Video Record (higher is better)
This test writes a single 720p HD video file to the NAS device employing 99.9% sequential 256kb writes.
Recording a video caused throughput to drop to the 15-18 MB/s range across all configurations which is to be expected when writing files across the network. The test results also show negligible benefits from either RAID 0 or jumbo frames here, although the write penalty is most evident in the RAID 1 configuration due to the performance hit required in mirroring the data to the second drive.
HD Playback and Record (higher is better)
The HD Video Playback and Record test combines the two previous tests and reads and writes a HD 720p video file simultaneously.
The DNS-323 still maintains decent throughput from 14-21 MB/s while simultaneously playing and recording a video. There were no real surprises here with RAID 0 and jumbo frames showing performance boosts, mainly due to the increased throughput as we saw on the playback tests.
Content Creation (higher is better)
This test simulates content creation on the NAS device such as might occur when rendering a video. There are 99 files used and is composed of 95% write operations with up to 64kb block sizes and consists of 39.1% sequential operations.
The content creation test really starts to put the DNS-323 under some pressure. After an initial set of reads, this test settles into writing a series of relatively small files which causes throughput to settle in around the 6.5 MB/s range without jumbo frames enabled and we see performance is consistent across all hard drive configurations.
Office Productivity (higher is better)
The Office Productivity test is roughly evenly distributed between read and write operations using 607 small files consisting of 1kb and 4kb reads and mostly 1kb writes.
This test is where things get really interesting. We see consistently lower results across all configurations with throughput around 2.6MB/s without jumbo frames enabled. The results of this particular test were concerning enough to cause me to re-run the tests several times to make sure there weren't any anamolies and the initial results proved correct. Still baffled, I e-mailed Intel support which confirmed these results were consistent with results they had seen with NAS devices in Intel's labs.
"We have seen circumstances similar to what you describe in our lab. Because the test is roughly 50/50 reads and writes there is a lot of buffered write data that must get to the drive while the NAS device continues to receive additional requests. Depending on their buffer management algorithms and how much memory is available on the NAS device, this type of heavy, bi-directional traffic can lead to reduced performance. This is most notable on those systems which tend to perform well on many of the other tests. The Office Productivity test is unique among the pre-configured tests because it includes both a large number of individual files and a heavy mix of read and write traffic."
So the conclusion we can draw here is that the DNS-323, with only 64MB of memory, can quickly become saturated under heavy loads to the point that performance is uniformly affected across all drive configurations.
File Copy to NAS (higher is better)
The File Copy test copies a single large file to the NAS unit using 100% sequential 64kb write operations.
Copying a single large file (1.4GB) shows the DNS-323 can pump data across the wire at speeds of 16MB/s and above. Here we see the effect of using just a single large file on performance versus the writing of many files of various sizes in the Directory Copy to NAS test below.
File Copy From NAS
This test reads the single large (1.4GB) file from the File Copy test from the NAS using 64kb read operations.
Bringing the single file back in the opposite direction, the DNS-323 is able to maintain speeds above 17MB/s without jumbo frames and the performance held fairly consistent across all hard drive setups.
Dir Copy to NAS (higher is better)
This test copies a directory structure with 126 files to the NAS device using predominately 64kb writes but also includes a wide distribution under 16kb.
Again, we see the effects of multiple consecutive writes as the unit's performance settles in around the low to mid 5MB/s range for all levels except the standard single drive configuration.
Dir Copy From NAS (higher is better)
This test copies the same directory structure of 126 files from the NAS device using 64kb reads.
Copying the test directory back to the host shows a marked improvement over the writing to the directory. It is interesting to see the performance delta on the directory copy to/from tests versus the pair of single file tests which were much closer together.
Photo Album (higher is better)
The Photo Album test simulates the viewing of 169 photo files of various sizes stored on the NAS and consists of 100% read operations.
Again we see a level of performance that is consistent across all setups as the test does a series of reads of various sized photo files.