QNAP TS-559 Pro Turbo NASJul 22nd, 2010 | By Anthony
At the steeper ends of the NAS scale, JBOD and RAID 0 are seldom used. Neither of these configurations offer data redundancy, and in the event of any individual physical disk failure the entire file system is at risk. JBOD, also known as a linear volume addresses each disk in the configuration as concatenations of a single virtual disk. A JBOD setup can be thought of as inverse partitioning where instead of a single drive separated to create logical drives a JBOD configuration concatenates two or more physical drives into one logical drive. Though JBOD is not particularly used with larger number of disks, or is necessarily the best choice for a disk setup, for consistency with our testing with smaller two or three bay devices and for the sake of reference we will address it and compare it alongside with RAID 0 and RAID 5 configurations. JBOD technically isn’t a RAID volume- rather it is known as a non- standard RAID volume and by design of combining independent disks, it is especially useful for combining assortments of drives with varying volumes. Where RAID configurations combine drives at the limit of the smallest disk, JBOD does not.
Starting with our first set of numbers, we see that partially due to the amount of memory in our test bed, and partially due to the system’s own memory and write cache, we see an enormous cache effect. Averaging out the measured throughput rates through each record size and normalized for Gigabit ethernet (125MB/s) the TS-559 Pro managed a write throughput of 118 MB/s.
Next, the Re- Writer test measures the system’s caching ability. It is typical that Re- Writer results are significantly higher than those reported in the Writer test as the test measures reading performance of a file that was previously read which is reflected in the enormous peak formation in the ranges of 32MB to 512MB file sizes. By default, for the EXT4 file system with QNAP’s newer firmware revisions write caching is enabled and appropriately, we saw it fit to reflect this in our data by running all tests with write caching enabled. In our Re- Writer we observed a transfer rate of 122 MB/s.
For read performance in the JBOD configuration, the TS-559 Pro managed 80MB/s.
Unlike with the Re- Writer test, our Re- Reader test indicated little difference when re-reading the same file. Performance showed no noticeable peaks and was comparable to the Reader test.
Next is a favorite among overclockers, gamers and performance users: RAID 0. RAID 0 splits data across usually two and occasionally more disks. Because of this, RAID 0, like JBOD is left without data redundancy and like a JBOD configuration: any individual disk failure causes the entire system to fail. RAID 0 typically isn’t used beyond two disks (unless in its hybrid form: RAID 1+0), and especially not in the network storage environment, but it does give us a few interesting data points and is a handy comparison against the more conventional, and practical RAID 5 configuration.
Performance of RAID 0 in many respects is similar to JBOD. Only, of course, a bit faster. For our Writer and Re- Writer tests, the TS-559 Pro hit 121 MB/s and 122 MB/s respectively.
With our Reader test in RAID 0, we have a very consistent just above 80MB/s throughput rate and on average, 82 MB/s.
And again, with the Re- Reader test, we do not see any difference in performance between the Reader or Re- Reader test. The NAS averaged 82 MB/s here as well.