Interface : three simultaneous accessesWe wanted to know the behavior of NAS when several PCs simultaneous access data. This was done by launching the reading of the collection of large files from three different machines and with three of the most common levels of Raid (0/1/5). Copying was carried out four consecutive times without interruption. We discarded the two extreme measurements for each machine and kept two in order to assure that results were coherent and then added the transfer rates. Obviously, we were mainly testing network interface capacities as NAS loads data into RAM. Here are the results obtained:
On all NAS, we can see that transfers are often almost perfectly balanced between the three PCs. The exception is the Qnap which systematically favors one machine over the two others.
The best results were obtained by the Thecus N4100+ and Buffalo, because each machine has a transfer speed rather close to the one in measured in a single access. In Raid 5, the cumulative speed is actually 2.8X that of a single access for the former and 2.4X for the latter. However, overall remember that they are both the poorest in simple access.
Synology seems to already make the best use of its interface capacities because it gains only 15% in Raid 5 but it is still better than Qnap’s 7%. The N5200BR Pro has a speed multiplied by 1.7 in Raid 5 and which is almost doubled in Raid 0.
Additional USB and eSATA Interface storage
All the NAS tested here have USB or even eSATA ports whose main use is to accommodate external hard drives in order to increase storage capacity.
Recognized file systems are at least Fat32 and NTFS, in reading only for the latter. The only exception is the Buffalo which doesn’t support the reading of Fat32 drives and it has to first format them in XFS. Obviously, it will then no longer be recognized in Windows.
To test the transfer speed on USB/eSATA ports we used Enermax’s Jazz casing which, equipped with a Micron JM20336 controller, offers a double USB/eSATA interface. We inserted a Seagate 500 GB drive, identical to those present in the NAS.
The Qnap posed a few problems and it was impossible to finish any bench as the connection to the USB drive was systematically lost after a few seconds of copying. However, after having formatted the drive in Ext3 (a Linux file system) rather than in Fat32, the problem disappeared. Obviously, there is the same compatibility problem as before.
Finally, copying the collection of large files proved to be impossible on the Thecus N4100+. The unit apparently didn’t recognize other file systems on its USB ports, and we couldn't find another way to run this test.
It is interesting to note that it is sometimes faster to write on an USB drive than on Raid 5 volume! This is especially true for Qnap, as well as for the collection of small files with Buffalo and Synology. The regularity of transfers, however, is sometimes affected as Qnap and Thecus are slower in the writing of large files than in that of medium size files.
Besides these particular cases, performances are between 9% and 30% inferior to Raid 5. In addition, we noticed that using the eSATA interface enables increasing performances by almost 50% on the N5200BR Pro !
In reading, the impact of processors integrated to NAS is less felt. In general, the difference is greater than with performances measured in Raid 5 (overall from 20% to 45%). The exception is the N5200BR Pro which is particularly efficient. The advantage of eSATA is still there but is considerably reduced.
USB keys and memory cards
We also tested NAS’ proper identification of various peripherals which we had in the office: two USB keys (an Intuix and generic model) and a Connectland multi-format memory card reader.
The keys were generally well recognized, although there were two exceptions. The names of files were cut off with the Buffalo NAS for the generic model while the Intuix key was seen as non-formatted with the Qnap. Also, note that because they were formatted in Fat32, the keys were only accessible in reading with the Terastation…
The memory card reader was not recognized by the Thecus NAS while the Buffalo and Qnap gave access to the first card inserted. As for Synology, it created a storage space for each memory card!
The USB peripheral download function offered by the N5200BR Pro and Qnap function well. After pressing the dedicated button on the face of the NAS, the system creates a new repertory and copies the totality of the USB peripheral’s stocked data. It is especially with the Qnap that this option is the most interesting because, in addition to offering a few supplementary copying options, it recognized our multi-card reader (unlike the Thecus models). This is practical for downloading the contents of a digital camera without turning on your PC.
You may recall that it is also possible to connect a printer on the USB ports for sharing amongst all the PCs on the network. However, this isn’t without its disadvantages. You no longer have access to the scanner on multi-function models and other options in the driver such as the ink level are no longer available.