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Written by Bruce Normann   
Monday, 19 March 2012
Table of Contents: Page Index
QNAP TS-879U-RP 10GbE NAS Server
Closer Look: 10GbE QNAP TS-879U-RP
QNAP TS-879U-RP NAS Hardware
NAS Testing Methodology
RAID 5 Test Results
Intel NASPT Test Results
ATTO Disk Benchmark Results
NAS System Overhead Measurements
NAS Server Final Thoughts
QNAP TS-879U-RP 10GbE Conclusion

NAS System Overhead Measurements

I've discussed the potential impact the NAS hardware has on performance in general terms so far. The hard reality is that the CPU, drive controllers, memory, and network subsystems have a direct and profound impact on the throughput of a NAS device. In extreme cases where multiple drives (4+) are arranged in higher-order RAID configurations, the CPU has a ton of work to do, calculating parity bits and parsing them out to multiple data streams. In-line data encryption adds another potential load to the infrastructure. In this section, I'm going to look at some results from the System Monitor capability that is available on the QNAP Turbo NAS server.

Let's start off looking at Network Bandwidth usage on the NAS server. During straight data transfers to and from the PC, with 8 disks configured as RAID 5 on the TS-879U-RP, the results show the single 10GbE connection consistently pushing and pulling over 500 MB/s of data through the wire. No real surprises here, just secondary confirmation that the data is actually being moved around from one place to another. You never know when an unsuspecting buffer will decide to make its presence known. The peak transfer rate during these tests is shown by a marker on the chart, and it's sitting at 586 MB/s. That's about 20% higher than the average throughput, which makes sense when you consider the effect of various system buffers and wait states. These charts had a lot more detail in them when each transfer took about 100 seconds to complete, now that they're over in about 20-25 seconds, the refresh rate of the chart is a little low.

QNAP_TS-879U-RP_Turbo_NAS_10GbE_Server_10GB_Transfer_NIC_P26.png

Now let's look at CPU usage on the NAS server for the same set of transfers. During straight data transfers the results show the Intel Core i3-2120 CPU still not being pushed to the max. Data writes to the NAS still consume more cores than reads, but the load really never gets higher than 50% on all cores. During Read tests, some of the additional "hyper-threaded" cores are doing close to nothing. They're involved, but only in a peripheral way. This is in marked contrast with every other NAS I've tested, where the CPU is maxed out at 100% when doing anything involving RAID. The Intel Atoms hold their own for the most part, but the Marvell processors have been a major bottleneck in my experience. Finally, with this corporate beast, we have a CPU that can handle the load. The memory subsystem on the QNAP TS-879U-RP is not being taxed by these file transfers at all. It's not even worth looking at the chart.

QNAP_TS-879U-RP_Turbo_NAS_10GbE_Server_10GB_Transfer_CPU_P27.png

Write tests with AES-256 volume encryption slow the transfer rate down quite a bit, and you can see from the marker on the chart that the peak was only 145 MB/s. The overall traces are pretty consistent, but the multiple small peaks in each transfer show some short-term variation in bandwidth. No surprises there, the refresh rate is pretty slow on these charts, and the various buffers and wait states always throw a couple wrinkles in any computer performance chart. In the next chart we'll see that the CPU gets hit hard, and in spikes - that's a factor that impacts the network throughput traces, as well.

QNAP_TS-879U-RP_Turbo_NAS_10GbE_Server_10GB_Transfer_NIC_AES_P28.png

Finally, let's look again at the CPU workload during disk write tasks with 256-bit encryption enabled. Reading the encrypted data doesn't tax the system as heavily, as far as I could see. With data encryption in the mix, the load on each of the CPU cores is much higher, spiking up to 100% quite often. Remember that these are virtual CPUs, as the Intel Core i3 2120 CPU has only two physical cores, but it supports Hyper-Threading. Also, the Core i3 does not support the recent AES-NI enhancements, so it's using brute force to encrypt this data. With the 10GbE interface keeping the bandwidth pipeline open, it looks like the CPU may have some bit of headroom left, but not much.

QNAP_TS-879U-RP_Turbo_NAS_10GbE_Server_CPU_AES_P14.png

I hope this section showed you some objective reasons why the infrastructure that any NAS product brings to the table is important to its overall performance. As the number of drive bays goes up, the hardware requirements increase as well, and the price has to follow. I know it's disheartening to see that you don't get great economies of scale on the larger NAS units, but it would be even more of a shame if they didn't perform up to their true capabilities because the hardware was holding them back. In this case, the network interface that definitely was holding the system back is no longer an issue, and the system is showing the balanced performance that is more typical with a well-designed NAS system.

Now that we've shown you all the performance information, I'll share some Final Thoughts and then move on to our Conclusion page.



 

Comments 

 
# Ok test 10GbE but ..Federico La Morgia 2012-03-28 01:54
Test with 8xocz agility3 raid-0 for the maximum performance on the transfer rate 10GbE???
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# RE: Ok test 10GbE but ..Olin Coles 2012-03-28 07:03
Sure! Would you like our address so you can send them to us?
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# RE: RE: Ok test 10GbE but ..Federico La Morgia 2012-03-28 07:36
Unfortunately I have not, however, try to ask them directly to OCZ
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# Might be fun, but...Bruce 2012-03-28 07:23
The results would be totally unrealistic. The great majority of users of this hardware are going to be stuffing it with mechanical HDDs, just because they need the capacity. I haven't seen any 2TB or 3TB SSDs around, have you? Also, anyone using an SSD in this type of application is going to have to use a very limited subset of SSDs - models that are specificallly designed for hard 24/7 RAID usage, without any TRIM support to keep the NAND cells fresh. The AGILITY uses "budget" flash memory, and any data center systems engineer who specified one for this kind of usage would be fired for incompetence.

So, I would be happy to use the QNAP TS-879U-RP to test some SSD makers' new enterprise-class drives, and run them hard, in a realistic test case. But, just stuffing some consumer grade devices in the NAS to push it closer to 10Gbps throughput doesn't really do much for me.... I "get" why QNAP tested it that way, but I also think it would have been useful for them to publish additional test results with enterprise-class HDDs.
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# RE: Might be fun, but...Federico La Morgia 2012-03-28 07:40
the case of 8xSSD SATA3 in Raid-0 (as well as also the same in Raid-6 both normal and degraded discs 1-2) is used to understand the goodness of the disk controller present and / or the ultizzo cpu in operations in which need for high performance!
Use the SSD so you need to understand the physical limitations inherent in the product, it is obvious that no one ever use this product with SSDs, but the fact remains that with the HDD will never get to know the limits of the Qnap as well as any 'NAS or other product that has or needs to introduce SATA mass storage.
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# SSD vertex 3Guy-Michel 2012-07-16 06:21
Hi we are planning use qnap either 879 or ts-ec879U-RP as a san unit for vmware it realistic? To boost performance we would could reuse ocz vertex 3 and 4 480.Second choice would be to put 480 ssd deneva from ocz for are database terminal server and accounting. would you recommand that? Or should we check to put the fastest sata available in raid 10 if supported.
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# RE: SSD vertex 3Olin Coles 2012-07-16 06:54
Please provide a little more detail. Will you use only one SSD, or several in RAID? Will the NAS receive backups, or merely run with redundancy?
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# detail in my mind :-)Guy-Michel 2012-07-16 07:09
would say that the main goal would be to have an array 4x480 vertex 4 let's say. the second array would be raid 10 fastest sata 6 we can find like Hitachi Deskstar 7K3000 or barracuda for file server and less critical vm machine.
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# further more detailGuy-Michel 2012-07-16 07:28
Just to complete obove my plan is to use the qnap like SAN for datastore in vmware esxi5.If test is speed wise acceptable we gone build arround that.While re-using are actual vmhost with individual ssd drive. we gone put these ssd in a QNAP with ISCSI SAN probably upgrade the ethernet to 10gige adapter and finaly bring a cluster for HA.that the overall plan. Be able to acheive HA whitout breaking the bank.
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# HA...??Bruce 2012-07-16 07:37
What is HA ?? I have never heard that acronym.
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# RE: HA...??Guy-Michel 2012-07-16 07:39
it is a accronym (H)igh (A)vailability.
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# RE: detail in my mind :-)Bruce 2012-07-16 07:32
Even though it says on the QNAP website: "...QNAP NAS supports advanced RAID configurations and multiple RAID volumes on a single NAS." I don't believe you can actually set up two separate RAID arrays on one NAS. Is that what you are proposing, two arrays of four drives each one one TS-879 machine? I don't think that's possible. Try posting that question on the QNAP forums, one of the QNAP representatives will give you confirmation.

You CAN set up multiple iSCSI targets and/or multiple LUNs one one device, but they would all reside on one physical RAID volume.
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# Lucky You...Bruce 2012-07-16 07:00
I would use the Enterprise Class SSDs if you can afford it. They have superior wear-leveling routines built into them. Remember, the operating system on the QNAP is not doing anything to keep the NAND refreshed on the SSDs, unlike consumer systems. I know OCZ and other vendors have been improving the "wear resistance" of all their SSD offerings, but the OCZ Denaeva will still have the most capable systems for keeping the performance up in this sort of usage.

RAID 10 (0r RAID 20)is usually best for database applications. RAID 5 can be slower in Write operations. Do you have the ability to set the system up in a test environment? I would strongly encourage that, so you can try the different configurations.
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# QNAP 10GbE PromotionBruce 2012-04-06 07:12
BTW, QNAP is bundling a 10GbE NIC with some models.
Details here: #qnap.com/static/landing/10gbe_en.html

Did I inspire them...? LOL
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# RE: QNAP 10GbE PromotionSébastien 2012-06-08 02:04
Any idea what transfer rate could be achieved if USB 3.0 was used instead of 10 Gbe (RAID5, same disks)?
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# At the max, maybeBruce 2012-06-08 08:10
From Wikipedia: The "SuperSpeed" bus provides a transfer mode at 5.0 Gbit/s additionally to the three existing transfer modes. The raw throughput is 4 Gbit/s, and the specification considers it reasonable to achieve 3.2 Gbit/s (0.4 GB/s or 400 MB/s) or more.

I got more than 450MB/s in ACTUAL real-world throughput, which is slightly more than the USB-IF expects the USB 3.0 connection to handle, so I would say that using USB instead of Ethernet would throttle the bandwidth somewhat. Of course, you lose all the advantages of having the device sitting directly on the network, which is a major feature of this and any other NAS.
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# USB 3.0Sébastien 2012-06-08 10:22
You are right but my plan is to share the NAS between 5 computers with slow streaming capability (connected to a 1 Gbe switch) and one or two close workstations with fast streaming capability (connected to the USB 3.0 ports). Do you know if this hybrid mode is supported? Do you confirm 450 MB/s with the NAS configuration you described and USB 3.0?

In case of simultaneous streaming what total throughput can I expect... could the NAS handle 2x450 + 100 MB/s = 1000 MB/s? That should be supported by 8 high end disks but I do not know if the processor can handle a RAID5 encoding/decoding at this rate...

Last question: is it possible to wire the NAS with two 1 Gbe cables to the switch and handle two 100 MB/s streams from two different computers? Is it seamless - I mean would the computers all see a single disk or is it more complex to aggregate?
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# Not recommendedBruce 2012-06-08 11:48
You are not going to be able to manage all these data streams with a quasi-network of USB connections connected to the TS-879U-RP.

Your best bet would be to get a 10GbE switch, like the one I mentioned from Cisco, in the review. That way, all your workstations can get the bandwidth they need, and you have the bandwidth for future expansion.
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# USB 3.0Sébastien 2012-06-08 12:35
Five of the computers connected to the NAS are old and run LOW profile hard drives (max 50 MB/s), it is very unlikely that more than 2 of them access the NAS simultaneously and none is equipped with 10Gbe adapters. Only a single (possibly 2 in the future) workstation is able to transfer data at a rate over 500 MB/s and it is the computer I expect to transfer the largest amount of data.

Given this situation I think that the 10Gbe switch + many 10Gbe adapters is overkilling... I thought USB 3.0 would be very well suited to this kind of unsymmetric and non simulataneous access scenario. Where do you exactly see a problem? Do you think that the hybrid mode cannot work in practice or were you only saying the NAS cannot handle two USB 3.0 streams at 450 MB/s?
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# Not too many 10GbE....Bruce 2012-06-08 13:02
The 10GbE switch I mentioned has only two 10GbE ports, the rest are all just GbE. That way, the individual workstation loads get aggreagated by the switch. The 10GbE ports are usually just fot rhe NAS, but you could put your workstation into one of them.

My main issue is that all the software for this, and most NAS devices, is designed and optimized to work in an Ethernet environment, not an ad-hoc USB network. The capabilities while connected via USB will be severly restricted. Upload and download, via a couple of built-in scripts, that's all.

FWIW, I'm never been impressed by the performance of USB with external drives. I guess I should test this one before I pull it apart...
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# RE: Not too many 10GbE....Sébastien 2012-06-08 13:38
I get your point and I have no doubt 10Gbe is well more efficient than USB 3.0 but I guess the price of the 10Gbe switch you mention would be well over the price of the NAS itself so I am afraid I cannot afford this extra cost. Still I would be really happy with the 450 MB/s you reported over USB 3.0 and I guess it will not interfere with the traffic over the 1Gbe port since the transfer will (a priori) not be simultaneous. My worry is more about the configuration of the system in ethernet / USB hybrid mode: is it prepared for this or is it thought to work exclusively in USB or ethernet mode?

Note: If you ever get the chance to test dual USB 3.0 transfer from two different computers ... :)

Thanks a lot for your help!
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# IT ConsultantsHenri 2012-11-14 23:26
Hi,
have such a box installed as ESXI 5.1 storage. Monday this week, the ESXI 5.1 freezed about 15 times after installing a additional RAID0 with 2 Samsung 830 512GB SSDs. Box is attached by 2* 10Gbit Intel X520 DA2.
Stopped to access this DataStore seams to fix the problem.
Support of QNAP always recommands to reset the box to the factory setup. Not very helpful.
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# Multiple RAID VolumesBruce Normann 2012-11-15 06:35
Does the firmware you are using support multiple RAID volumes? Last time I checked you couldn't do that. Multiple LUNs, yes....but that's not the same thing as a new RAID volume. There are some devices out there thad support multiple volumes, just not sure if QNAP added that capability since I last inquired.
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