| QNAP TS-879U-RP NAS Network Storage Rack Server |  |
| Reviews - Featured Reviews: Network | |
| Written by Bruce Normann | |
| Tuesday, 07 February 2012 | |
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Page 13 of 16
1GB RAID 5 Test ResultsIf you've got more than three HDD spindle to put in play, it makes sense to use one of the more advanced RAID configurations. RAID 5 is one of the most popular setups, primarily due to the balance it exhibits between capacity and redundancy. Not surprisingly, most NAS units that can support more than three HDDs also support RAID 5, so it makes sense to use it for test purposes. 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. I am fortunate to have purchased eight W-D Caviar Black 750GB drives before the floods in Thailand wiped out half the world's HDD production capacity. The results for RAID 5 read testing are very similar to single disk testing, which is not a bad thing. Given all the behind-the-scenes processing that goes on to calculate parity bits, these results show that most QNAP Turbo NAS units have the necessary power under the hood to keep the drives performing at their highest potential during read operations. When using RAID 5, the TS-879U-RP outperformed all of the other NAS systems and came close to its own performance level in single-disk operation. There was virtually no difference between 4-disk and 8-disk performance. CPU, memory, and network utilization were almost identical too, which tells me the support hardware has plenty of muscle to handle the task of pushing around all eight disks. Read performance is clearly very strong with this system, which is a real bonus if you use it as frontline storage. Using it primarily as a backup system, you want top-notch write performance, which we'll test next. 
The 1 GB RAID 5 disk write test stays right up there with the single disk results. It's well known that RAID 5 write performance can be a weak point, with all the computation overhead involved and the extra parity bits that need to be calculated and written to each of the drives. The only way to overcome that is with raw computational horsepower, which is what the TS-879U-RP brings to the table better than any other NAS in this test. It's a shame that the simplest task any NAS can perform is basic backup duty, and in order to do that well, you need to buy the most powerful system to effectively reap the benefits of a multi-disk array. The reduced write performance with 1500 MTU is also a factor in RAID 5, so it's looking more and more like Jumbo Frames (9000 MTU) should be the preferred network setting for this unit. Unfortunately, you can't take advantage of Link Aggregation at that setting, as it is limited to 1500 MTU.
Next up is 10 GB (1000 metric megabytes / 10,000,000,000 bytes) file transfer testing. Using the 4-disk RAID 5 configuration in each NAS, and a single Gigabit connection, network throughput will be put to the test, and the effect of any system or hardware caches will be minimized. I'll also include some 8-disk results, just because I can. 10GB RAID 5 Test ResultsLooking at read tests with a single 10GB file, the TS-879U-RP still beats out all of its little brothers, but not as much as in some of the other tests. The TS-659 Pro II improved its performance when transferring large files; it shows how this unit is built to carry the heavier data loads. The TS-879U-RP takes it a step further and comes in first place as a result. The proof of that is the nearly identical performance between 4-disk and 8-disk operation. There is still a small decrease in performance with Jumbo Frames disabled, which is now consistent between Read and Write tests, as we'll see in a moment. It's not significant enough to outweigh the reliability and availability advantages of Link Aggregation, though. Not in a corporate LAN room, or anywhere else.
Looking at write tests with a single 10GB file, the TS-879U-RP smokes the smaller units with gains of 50% and 100% over the Intel Atom and Marvell-based models. If you're writing large files to a NAS, you can't afford to scrimp on system hardware; you need the biggest, baddest CPU you can afford. The other units still suffers from the typical RAID 5 write penalties due to the computing overhead required to deal with the parity bits. The various caches built into the host and target system help out on the smaller file transfers, but they get filled up and lose their effectiveness when dealing with large files like this. Once again, the TS-879U-RP just laughs at the additional load of four additional hard drives; the CPU utilization never got above 25%. Once again, the 1500 MTU results lag a little bit behind the Jumbo Frames performance, but the redundancy of the dual GbE interfaces in a teaming arrangement trumps the small loss in throughput. The bigger issue is that the TS-879U-RP is being completely throttled by the 1000BASE-T interface, and really can't perform at its best without one or two 10GbE connections.
All in all, my impression of the test results is that the QNAP TS-879U-RP puts in a solid performance, eeking the most out of the GbE interface that comes standard. Judging by the System Overhead measurements that I'll show you in the next section, the TS-879U-RP doesn't even break a sweat when its throughput is limited by the network connection, at 1000 megabits/second. It's performance is suited for any task you might think of: front-line storage, backup, replication, or any combination. Its iSCSI capability means you're not limited to a single application, and the VMware capability means it's at home in virtualized environments, as well. Now, let's take a closer look at the internal workings of the NAS, where we can see the individual activity of the CPU, memory, and network interface. It's these support subsystems that have a big influence on the overall system performance, as I've demonstrated in the past. NAS Comparison Products
EDITOR'S NOTE: We've retested this product using 10Gb Ethernet, which gave phenomenal results. Read more here: QNAP TS-879U-RP 10GbE NAS Server
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