Timing buffered disk reads: 424 MB in 3.01 seconds = 140.85 MB/secĬomparing the value of sda (502MB/s) with the performance metrics of, we notice that the performance is excellent, among the highest values. ![]() Timing buffered disk reads: 1512 MB in 3.00 seconds = 503.66 MB/sec Timing buffered disk reads: 426 MB in 3.01 seconds = 141.39 MB/sec Timing buffered disk reads: 1510 MB in 3.00 seconds = 502.52 MB/sec Timing buffered disk reads: 420 MB in 3.00 seconds = 140.00 MB/sec Timing buffered disk reads: 1508 MB in 3.00 seconds = 502.18 MB/sec So we see that sda is 3.6 times faster than sdb in reading: /dev/sda: In this example, sda is an SSD, and sdb is an HDD: # for i in do hdparm -t /dev/sda hdparm -t /dev/sdb done Let’s try to compare two disks by repeating the measurements three times. All disks have some wear with writing, so running tests that repeat writing in the same locations thousands of times can shorten their lives.Īccording to the manual page, we’d best repeat this benchmark two or three times on a system with no other active processes and at least a couple of megabytes of free memory. We should also be careful not to subject our disks to overly stressful benchmarks. The best benchmark criterion is our actual workload. Still, unlikely cases rarely provide useful performance data. We can push our disks to unrealistic edge cases that will never occur in our workstation or server. software, such as the operating system and driversĪn additional problem is figuring out what we want to measure.testing hardware, such as CPU, interface, chipset.Let’s also keep in mind that benchmark results can be affected by: On the other hand, if we use a random generator, we will measure that one and not the disk. In fact, some filesystems and disks handle writing zeros and other compressible data in a particular way, which will cause benchmark results to be too high. dd is popular because it comes preinstalled on almost all Linux distributions, but it can give us unrealistic results. First, let’s avoid using dd to test the speed of writing zeros or random data.
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