A variety of value-added services is often why people choose NAS as their file server. However, when you ask someone about NAS, you always get different feedback about the quality and performance of these services – and it’s a mystery that’s worth exploring. Today we’re going to dig little more into the different ways people use their NAS, as well as the performance differences.
Let’s take a NAS we use at home as an example. Digital photos and HD films are transferred to a NAS server via our computer, which will take some time during the transfer. So it’s safe to say the speed at which the files are being transferred will determine the quality of the service, which raises another question– how fast can I get my files to my NAS? Today we are going to unfold the things that Synology has done to improve file transfer performance.
How we conduct the tests
To make the test results to be as useful, we try to make the way we test close to real-life experience. We used Windows 7, with the Robocopy command to transfer files to NAS server just like the Windows Explorer with SMB protocol.
In the performance test, we put together 10,000 x 1MB photo files. As for HD video, the file is at about 5GB each. These two testing environments and parameters are going to let us look at the performance results for small and large file transfer.
Using Robocopy command, we calculated the time it took for the above two types of file to transfer to a testing NAS server. In order to create a comparative environment, we placed Synology DS212 with other NAS servers of the same specifications on the market. In the chart below, you can see that in the first row we have DS212 and three other NAS servers; and hardware specifications of client PC’s .
|Synology DS212||NAS 2||NAS 3||NAS 4|
|CPU||Marvell 6282 1.6G||Marvell 6282 1.6G||Marvell 6282 1.6G||Marvell 6282 1.6G|
|Memory||DDR3 256MB||DDR3 256MB||DDR3 256MB||DDR3 512MB|
|Raid type||RAID 1||RAID 1||RAID 1||RAID 1|
- Network Environment: 1Gbps LAN; MTU 1500; directly connected to the client PC
- NAS: HE103UJ HDD x 2
- Client PC: Intel Core i5 750 2.67GHz; 4GB DDR3; WD3000HLFS (10K RPM, 300GB) HDD x 2, RAID 0; Intel Gigabit CT; Windows 7
Writing Large Files to NAS
Let us first look at the transfer performance for large files. As you can see in the diagram below, Synology’s NAS server offers the best write-in performance for large files among the competitors. Our users will be able to copy a large quantity of multimedia content in a very short time, which we believe is what matters to most people. Just recently, we released a software patch aiming to optimize write-in performance for ARM-based platform models  – hoping to provide a complete user experience for our customers.
In addition to large video file transfer (5GB), transferring massive quantity of small files is also a common practice seen for everyday use on a NAS. So let us look at how this turns out from our testing.
Writing Small Files to NAS
The chart above reflects the ability that Synology products have in terms of performance. We are able to allow our users, when transferring photos or office documents, to get the best out of the service we provide. Until now, I am sure you are wondering about the same thing – why is there such a huge difference in terms of performance between large file and small file?
The answer is that each type of write-in is confronted with different challenges. Before going into getting the write-in performance up for small file transfer, we have to address the issue of how to search files that have the same name tag under the same level of directory effectively. The searching and the files are keys to affecting our performance tests. Well, we overcame the search issue with specifically designed optimization techniques. Together with the ARM-based optimization technology we mentioned earlier, the overall quality and performance for small file is proved to be greatly enhanced. So let’s now look at how and what we did to achieve this improvement.
Generally speaking, if we were to use the same testing methodology and parameters on Linux-based servers, the write-in performance will be inversely proportional to the number of files in the directory – the more files there are in the same level of directory, the slower the speed at which they are being transferred. This is mainly because the host server has to search for any file with the same name to decide whether a file can be written in or not. We see a particular curve (see below) in terms of network utilization during a performance test we did on small file transfer using Linux-based Ubuntu or Fedora.
Small file transfer on Ubuntu 10.10 
The decreasing trend can be explained by the description we discussed earlier about file search. So if you want to transfer a large quantity of photos to Fedora or Ubuntu-based server, you will certainly see the overall transfer performance being affected by the number of photos. For this we also have our own solution: the file transfer performance on Synology products will not be hindered regardless of the number of files. Here is a display of the Internet usage during a performance test we did on an optimized DS712+ using the same batch of files.
Small file transfer on DS712+ 
Compared to Linux-based servers in general, we optimize our search technology so that the writing speed will stay constant regardless of the number of photos or office documents that are being transferred. This enhancement applies to all our Synology products.
Today we went deeper about the performance of file transfer on NAS by showing testing results we did. We would like you to understand the mystery behind the services on Synology NAS in terms of performance, especially file transfer. Our Synology® ARM® Performance Acceleration Technology optimizes the write-in performance on Synology products. The results were shown in our small file transfer testing as well. Furthermore, we will continue to set speed and performance as our foremost goal to improve on, and everyone can enjoy Synology products.
 Synology® ARM® Performance Acceleration Technology. Click here for more detailed information.
 Click here to see product spec of Synology DiskStation DS712+