How does it work?

• create a file with size length
• rewrite random 4 kbyte in file (or readwrite, -r)
• measure the time: time(N * [4kbyte (rd)wr & sync]) / N is the time of the rewriting of 4kbyte block
• the intermediate sync can be skipped (-a), the sync will be at the end of all rewrite.
• see --help

Build and running

$ cargo build --release
$ ./target/release/hdd-speed-test -h

$ ./target/release/hdd-speed-test -s 8192 -r   # first run, create file
$ ./target/release/hdd-speed-test -s 8192 -r   # only test (file already exists)

$ rm testfile.dat                              # at the end of tests, remove manually

Measured values:

• 4 TB HDD (WD40EZRX) software raid1
  • ext4: 23.18 msec/4k (first part of disk) and 48.80 msec/4k (last part of disk)
  • btrfs: ??? msec/4k (first part of disk) and 167.80 msec/4k (last part of disk)
• 960 GB SATA (KINGSTON SEDC600) software raid 1 (CPU: Xeon(R) Silver 4116)
  • ext4: 0.067 msec / 4k (-n 10000)
• 7,68 TB U.2 (KINGSTON SEDC1500M7680G) software raid1 (CPU: Xeon(R) Silver 4116)
  • ext4: 0,051 msec / 4k
  • btrfs: 0,620 msec / 4k (copy on write filesystem)