|QNAP TS-879U-RP NAS Network Storage Rack Server|
|Reviews - Featured Reviews: Network|
|Written by Bruce Normann|
|Tuesday, 07 February 2012|
Page 11 of 16
Benchmark Reviews primarily uses metric data measurement for testing storage products, for anyone who is interested in learning the relevant history of this sore spot in the industry, I've included a small explanation below:
The basic unit data measurement is called a bit (one single binary digit). Computers use these bits, which are composed of ones and zeros, to communicate their contents. All files are stored as binary files, and translated into working files by the Operating System. This two number system is called a "binary number system". In comparison, the decimal number system has ten unique digits consisting of zero through nine. Essentially it boils down to differences between binary and metric measurements, because testing is deeply impacted without carefully separating the two. For example, the difference between the transfer time of a one-Gigabyte (1000 Megabytes) file is going to be significantly better than a true binary Gigabyte (referred to as a Gibibyte) that contains 1024 Megabytes. The larger the file used for data transfer, the bigger the difference will be.
Have you ever wondered why your 500 GB hard drive only has about 488 GB once it has been formatted? Most Operating Systems utilize the binary number system to express file data size, however the prefixes for the multiples are based on the metric system. So even though a metric "Kilo" equals 1,000, a binary "Kilo" equals 1,024. Are you confused yet? Don't be surprised, because even the most tech savvy people often mistake the two. Plainly put, the Kilobyte is expressed as 1000 bytes, but it is really comprised of 1,024 bytes.
Most network engineers are not fully aware that the IEC changed the way we calculate and name data chunks when they published the new International Standards back in December 1998. The International Electrotechnical Commission (IEC) removed the old metric prefixes for multiples in binary code with new prefixes for binary multiples made up of only the first two letters of the metric prefixes and adding the first two letters of the word "binary". For example, instead of Megabyte (MB) or Gigabyte (GB), the new terms would be Mebibyte (MiB) or Gibibyte (GiB). While this is the new official IEC International Standard, it has not been widely adopted yet because it is either still unknown by institutions or not commonly used.
NAS Testing Methodology
All the NAS devices we test cannot accommodate all the different disk configurations, so our current test protocol has been based on two of the most popular setups: a basic (single) disk and RAID-5 configurations. Most NAS products that can support RAID 5 go beyond the minimum number of drive bays, to a total of four, so that is the number of drives that I typically use to test with, even though I could get by with only three. I also took advantage of the massive capacity that the QNAP TS-879U-RP offers, and tested it with the full complement of eight drives. During initial setup, the NAS was upgraded to the latest v220.127.116.116 firmware by flashing the DOM with binary files from QNAP's website. The firmware installed on the TS-879U-RP was v3.4.3.0331 when I recieved it, and the same version was included on a CD-ROM provided in the accessory kit.
Connected directly to two identical Intel Gigabit CT Desktop LAN controller in the test-bench system by ten-foot CAT6 patch cables, the NAS product receives one test transfer followed by at least three timed transfers. Each test file was sent to the Western Digital Caviar Black 750GB (WD7502AAEX) hard drives installed in the NAS for a timed write test, and that same file was sent back to the OCZ Agility3 120GB SSD (AGT3-25SAT3-120G) in the test system to perform a read test. Each test was repeated several times, the high and low values were discarded and the remaining results were recorded and charted.
The maximum data transfer rate that can be expected from the host computer is a function of several things, but one thing's for sure. The data has to be written to, or read from the drive on the host, 10GB at a time. For this test I'm using the third generation OCZ Agility SSD, which will be good for at least 500 MB/s, in or out. If I need higher throughput, I'll end up installing some RAMDisk software and borrow 10 GB from the sixteen that I have installed as system RAM. For now, here's a validation run of ATTO Disk Benchmark on the OCZ Agility 3 SSD in the host system, just to show what a 3rd generation SSD on the Sandy Bridge platform is capable of.
We are continuing our NAS testing with the exclusive use of Windows 7 as the testing platform for the host system. The performance differences between Win7 and XP are huge, as we documented in our QNAP TS-259 Pro review. The adoption rate for Win 7 has been very high, and Benchmark Reviews has been using Win 7 in all of our other testing for some time now. It was definitely time to make the jump for NAS products.
The two Read and Write transfer tests were conducted on each NAS appliance using the 1 GB file and then a 10 GB file. Additionally, a second set of tests were conducted with Jumbo Frame enabled, i.e. the MTU value for the Ethernet controllers was increased from 1500 to 9000. All the NAS products tested to date in the Windows 7 environment have supported the Jumbo Frame configuration. In the case of the TS-879U-RP, I tested the 1500 MTU setting with two NICs operating in IEEE 802.3ad mode. This is commonly called Link Aggregation Control Protocol (LACP), and I set the two cards to use dynamic link aggregation. Not all network interfaces will support this level of control, but the device drivers on the QNAP do, and I used Intel's Advanced Networking Services (ANS) driver on the host PC's NICs.
I also include a baseline of sorts on the single disk charts, which is the internal file transfer from a Corsair P64 SSD to a Western Digital 150GB VelociRaptor installed on an Intel P55 motherboard SATA connections, where the Intel P55 chipset provides the SATA 3Gb/s interface, and a Marvell 88SE9123 controller provides two ports of SATA 6Gb/s connections.
NAS Comparison Products