The first two tests use a single thread, but 32 outstanding IO. This basically makes these two tests worthless in even a single disk environment - let along for an All-Flash Array. The second two tests run with only a single outstanding IO (-o) and a single thread (-t) - nowhere near enough to test even a single disk, and it also turns the testing into not a test of IOPS/bandwidth, but instead just a latency test (see Queue Depth, IOPS and Latency to understand why). Each of these tests is run a configurable number of times (1-9 times, defaulting to 5), so that at least brings us up to 25 seconds per test by default - but that's still not even close to enough for realistic results. Each test is only being run for 5 seconds - far to short to get anything close to a realistic result, especially for write tests where 5 seconds of data will never make it beyond the cache. The first thing that stands out from this table is the -d option - the duration of the test. The options passed to Diskspd for each of the tests was : Test The details on exactly what each of these tests does is vague, so I grabbed the command-line it's passing to diskspd for each of them to see exactly what they are doing. Then for each test there is a read and then write phase run (interestingly, all read tests are run first, followed by all of the write tests). The first two tests are implying a queue depth of 32 and 1 thread for sequential and then "4K" IO, followed by the same two tests with no mention of queue depth/threads. The UI for CrystalDiskMark gives a fairly clear idea of the tests that it runs : The data written during write tests can be made somewhat unique, but requires massive amounts of memory to do soĬrystalDiskMark does actually make an effort to overcome the first of these issues, but unfortunately it's target market means that it fails in countless other ways as a suitable tool for testing AFA's.The initial test file written by Diskspd contains completely unique data.Unfortunately diskspd itself is not a good tool for testing storage that supports de-duplication - see my separate post on Diskspd for the full details, but in short : DiskspdĪccording to their website, CrystalDiskMark is basically just a front-end to Microsoft Diskspd. CrystalDiskMark is the type of tool I wouldn't even normally look at due to it's focus market, but one of our SE's asked about it last week, so.ĬrystalDiskMark is a tool you would normally see used on standalone hard disks/SSD, in particular on consumer focused websites like Toms Hardware - not on enterprise All-Flash Arrays.
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