Random Performance – Iometer (IOPS/latency), YAPT (random)

We are trying something different here. Folks tend to not like to click through pages and pages of benchmarks, so I'm going to weed out those that show little to no delta across different units (PCMark). I'm also going to group results performance trait tested. Here are the random access results:


Iometer is an I/O subsystem measurement and characterization tool for single and clustered systems. It was originally developed by the Intel Corporation and announced at the Intel Developers Forum (IDF) on February 17, 1998 – since then it got wide spread within the industry. Intel later discontinued work on Iometer and passed it onto the Open Source Development Lab (OSDL). In November 2001, code was dropped on SourceForge.net. Since the relaunch in February 2003, the project is driven by an international group of individuals who are continuously improving, porting and extend the product.

Iometer – IOPS

In pretty much every test that involves writes (all but Web Server), we see occasional dips in IOPS performance of the RD400. This legacy test attempts to get its figures from an *unfragmented* SSD and its runs are very short, meaning that if an SSD has intermittent dips in performance, those dips will translate to dips in the chart. So with these results, we can pretty much establish that there *are* dips where write workloads are involved, but the extent of those can only be further explored with our newer and far better Latency Percentile testing, which appears on the next page.

Iometer – Average Transaction Time

For SSD reviews, HDD results are removed as they throw the scale too far to tell any meaningful difference in the results. Queue depth has been reduced to 8 to further clarify the results (especially as typical consumer workloads rarely exceed QD=8). Some notes for interpreting results:

  • Times measured at QD=1 can double as a value of seek time (in HDD terms, that is).
  • A 'flatter' line means that drive will scale better and ramp up its IOPS when hit with multiple requests simultaneously, especially if that line falls lower than competing units.

The above latencies are average figures. If you want far greater detail on this data (and to figure out what caused that nasty QD=4 spike in the workstation latency plot), simply flip to the next page!

YAPT (random)

YAPT (yet another performance test) is a benchmark recommended by a pair of drive manufacturers and was incredibly difficult to locate as it hasn't been updated or used in quite some time.  That doesn't make it irrelevant by any means though, as the benchmark is quite useful.  It creates a test file of about 100 MB in size and runs both random and sequential read and write tests with it while changing the data I/O size in the process.  The misaligned nature of this test exposes the read-modify-write performance of SSDs and Advanced Format HDDs.

YAPT is a 'misaligned' test, in that it does not adhere to 4k boundaries. The RD400 didn't agree with it (as was the case with the Intel SSD 750). Moral of the story – ensure your SSD partitions are 4k aligned. This is not an issue if creating the partition with Windows 7 and up installers, but some cloning software may not adhere to these boundaries when moving to a new drive.

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