In Linux, the
dd command can be used for simple I/O performance measurements
$ dd if=/dev/zero of=/root/testfile bs=1G count=1 oflag=direct 1+0 records in 1+0 records out 1073741824 bytes (1.1 GB) copied, 32.474 s, 33.1 MB/s
Here the test took 32.474 seconds to run and 33.1 MB/s was the actual disk speed. Don’t forget to delete the test file when finished.
if: input file;
of: output file;
bs: sets the if and of sizes to bytes; block size (base 10 integer, 1G=1024×1024×1024 bytes = 1.073 GB);
count: number of blocks (1 means that 1 block of 1G is copied);
oflag=direct: uses direct I/O data, avoiding the buffer cache; and it speeds up the process 1.