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QNAP TS-451+ NAS Review

Four-Corner Performance Testing

We've updated our comparison units now that we have a sufficient number of mid-range models in the database. In the coming months, we'll publish reviews of Asustor's AS6104T and Netgear's ReadyNAS 214. You can read our review of the Thecus N5810 Pro here.

All of the systems in today's review are filled with Seagate NAS 4TB disks in RAID 5, and they run from a single GbE port through an enterprise switch.

Sequential Data Transfer by Block Size

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The sequential read performance for every system is similar at each block size. This isn't a very stressful metric, but it does give us some idea of what to look for as our testing continues.

There's a lot more variation in the sequential write test. Asustor's AS6204T is on the first iteration of the company's newest operating system, and it clearly has some issues with smaller block sizes. The TS-451+ finishes without encountering any issues; it performs particularly well in the 64KB and 128KB tests, posting bigger numbers than Thecus and Western Digital.

Sequential Performance

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Now we're looking at 128KB and 1MB blocks, charted across increasing queue depths. Interestingly, the mid-range systems we're measuring don't report higher throughput as queue depths go up. That would normally be bad. But many of these platforms saturate a GbE link at low queue depths, so that's our bottleneck.

The write tests again yield a wider range of performance results. QNAP's TS-451+ performs well, managing to saturate the gigabit Ethernet connection.

Sequential Mixed Data Sweep

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All of the systems are optimized for workloads consisting of 80 percent reads. Back when the SSD 520 launched, Intel published a document claiming that 80 percent reads are typical for most client systems. Seventy percent reads are more common among workstations.

The bathtub curve observed here is what we're accustomed to. After all, mixing reads and writes presents a greater challenge than a pure read or pure write workload.

Random Data Transfer by Size

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For the most part, if you don't run applications on the NAS or use the appliance as an active disk with a mapped volume, you will rarely transfer files in a random manner. Even when you send small blocks of data over SMB, the information moves sequentially. Hosting an app on the NAS is another story entirely, though.

In both the read and write tests, QNAP's TS-451+ outperforms its competition in random 4KB performance. This is important for running applications with Windows, where 4KB blocks make up a majority of the workload. The 8KB block size is often associated with virtual machines from VMWare. The TS-451+ also outperforms the other products there, though it falls behind two systems in 8KB random writes. 

Random Performance

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Ratcheting up the random workload by scaling queue depth doesn't do much for performance. For the most part, these systems demonstrate fairly linear performance as the queue depth increases. 

Random Mixed Data Sweep

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Under heavy random writes, all of the systems use cache algorithms to burst performance. None of them exhibit a bathtub curve as we sweep across the mixed workloads. We see very little variation until the test's end, where caching performance differentiates each appliance.

Chris Ramseyer
Chris Ramseyer is a Contributing Editor for Tom's Hardware US. He tests and reviews consumer storage.