| OCZ Vertex-2 Extended Solid State Drive |  |
| Reviews - Featured Reviews: Storage | |
| Written by Olin Coles | |
| Thursday, 08 July 2010 | |
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Page 5 of 12
SSD Testing MethodologySolid State Drives have traveled a long winding course to finally get where they are today. Up to this point in technology, there have been several key differences separating Solid State Drives from magnetic rotational Hard Disk Drives. While the DRAM-based buffer size on desktop HDDs has recently reached 32 MB and is ever-increasing, there is still a hefty delay in the initial response time. This is one key area in which flash-based Solid State Drives continually dominates because they lack moving parts to "get up to speed". However the benefits inherent to SSDs have traditionally fallen off once the throughput begins, even though data reads or writes are executed at a high constant rate whereas the HDD tapers off in performance. This makes the average transaction speed of a SSD comparable to the data burst rate mentioned in HDD tests, albeit usually lower than the HDD's speed. Comparing a Solid State Disk to a standard Hard Disk Drives is always relative; even if you're comparing the fastest rotational spindle speeds. One is going to be many times faster in response (SSDs), while the other is usually going to have higher throughput bandwidth (HDDs). Additionally, there are certain factors which can affect the results of a test which we do our best to avoid. SSD Testing DisclaimerEarly on in our SSD coverage, Benchmark Reviews published an article which detailed Solid State Drive Benchmark Performance Testing. The research and discussion that went into producing that article changed the way we now test SSD products. Our previous perceptions of this technology were lost on one particular difference: the wear leveling algorithm that makes data a moving target. Without conclusive linear bandwidth testing or some other method of total-capacity testing, our previous performance results were rough estimates at best. Our test results were obtained after each SSD had been prepared using DISKPART or Sanitary Erase tools. As a word of caution, applications such as these offer immediate but temporary restoration of original 'pristine' performance levels. In our tests, we discovered that the maximum performance results (charted) would decay as subsequent tests were performed. SSDs attached to TRIM enabled Operating Systems will benefit from continuously refreshed performance, whereas older O/S's will require a garbage collection (GC) tool to avoid 'dirty NAND' performance degradation. It's critically important to understand that no software for the Microsoft Windows platform can accurately measure SSD performance in a comparable fashion. Synthetic benchmark tools such as HD Tach and PCMark are helpful indicators, but should not be considered the ultimate determining factor. That factor should be measured in actual user experience of real-world applications. Benchmark Reviews includes both bandwidth benchmarks and application speed tests to present a conclusive measurement of product performance. Test System
Drive Hardware TestedThe following storage hardware has been used in our benchmark performance testing, and may be included in portions of this article:
Test Tools
Test Results DisclaimerThis article utilizes benchmark software tools to produce operational IOPS performance and bandwidth speed results. Each test was conducted in a specific fashion, and repeated for all products. These test results are not comparable to any other benchmark application, neither on this website or another, regardless of similar IOPS or MB/s terminology in the scores. The test results in this project are only intended to be compared to the other test results conducted in identical fashion for this article.
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Comments
BTW. iometer is highly affected by compression - I have no troubles reaching ~45000 IOPS with my older Indilinx based SSD on a compressed NTFS partition.
Thomas
I will email you my Iometer configuration file, so that you may reproduce our test exactly as we conduct it. Please be informed that all SSDs are wiped clean using DISKPART "clean all" prior to testing. Also note that this is the total IOPS reported by the test, and not an individual read or write.
Do you think this is totally controller related?
BTW, sanity erase or a format of the whole drive (not a quick format) under win7 with a TRIM enabled AHCI driver+controller will restore the factory performance, not sure if a "diskpart clean all" will do the same.
Thomas
Thank you for bringing this to our attention. These specification are pulled directly from the manufacturer-supplied data sheet, and are often subject to change without notice. I would consider the specifications listed on the website to be the most current and accurate.