There are a wide range of synthetic test suites available, so I’m just going to give a quick guide to the most common widely used tools:
CrystalDiskInfo – This is actually just a drive information tool, useful for showing the drive’s capabilities such as whether it supports Native Command Queuing (NCQ), TRIM and so on.
HD Tune (Pro) – A benchmark tool which bypasses the file system level. It started off as freeware tool to show the sustained read performance across a hard disk’s platter, access performance, burst rate and CPU usage. For an SSD, the read performance graph usually remains fairly flat and gives an idea of what the SSD is capable of sustaining. The newer HD Tune Pro software which must be purchased can also carry out a wide range of transfer size tests, such as to show IOPS performance, average access time and throughput. As far as I’m aware of, in the write tests, the data supplied by HD Tune Pro is compressible, showing the best case scenario for SSD controllers that compress data.
HD Tach – Like HD Tune, this also bypasses the file system level and actually works at a low disk access level. This tool is available by request from Simpli software and is current free. This tool also shows sustained read and write performance, random access performance and how it compares with other drives. As far as I can tell, its sustained writing involves uncompressed data, again showing a best case scenario.
ATTO – This is a very popular benchmark carried out on a wide range of storage media, including external flash drives and hard disks and works at the file system level. This shows the drive’s reading and writing performance at the file system level using different transfer sizes. The tool operates by default at a queue depth of 4, which is the equivalent to four threads or applications simultaneously accessing the drive. ATTO’s data is uncompressed and is commonly used to show the maximum read and write rates an SSD is capable of delivering with the best case scenario of the data being highly compressible. Note that SSDs with large caches tend to show higher transfer rates and what they are capable of sustaining.
CrystalDiskMark – This is another popular benchmark which also works at the file system level. This carries out sequential, random 512KB and 4KB read and write operations. The 4KB test is also repeated at a queue depth of 32. Each test is run 5 times by default with the best result shown when complete. By default, CyrstalDiskMark uses random uncompressible data, showing a worst case scenario for SSDs affected by data compressibility, such as where the SSD is used for storing JPEG images or other types of data that cannot be easily compressed. There is an option to run the test with 0 or 1 fill, to show the best case scenario, which is useful for if the SSD is used for storing compressible data such as in a file server storing large a quantity of text documents and spread sheets.
AS SSD – Unlike most other tests, this benchmark is specifically designed to benchmark SSDs. The benchmark consists of several tests, again covering sequential, random 4KB IOPS and threaded random 4KB IOPS. Each test is conducted over a longer period of time to overcome drive’s cache which can potentially show higher better results in shorter tests. The benchmark uses random uncompressible data in its tests, showing the worst case scenario.
Unlike most other benchmarks, AS SSD also delivers a score, which makes it easier to compare SSDs. In general, a higher score relates to a faster SSD in the real world. The tool can also run file read/write simulation tests and measure sequential transfer rates under various levels of data compressibility. .
IO Meter – As its name suggests, this test is specifically designed to measure IOPS performance. Unlike other benchmarks, each test is individually run and can be heavily customised, such as with different block sizes, queue depths, multiple worker threads and a user set length of time.
Samples can be taken throughout the test such as with a screen capture application to show how the drive performs as the runs over several minutes, especially in write testing. IOMeter is very good at discovering weaknesses such as where an SSD would show a very good result in CrystalDiskDisk mark, but struggles in the real world such as when faced with studio recording software that records a large number of simultaneous tracks over a period of 5 or more minutes.
Many reviewers run customised IO Meter tests to give an idea of how the drive would perform in a database server, web server or file server.