Wednesday 1 August 2012

SSD / HDD benchmarking on Linux

Found this gem of a wiki on archlinux the distro for speed.
https://wiki.archlinux.org/index.php/SSD_Benchmarking

There are several HDD benchmarking utils/ways
some like dd (see exerpt below) are avail on all linux systems by default and good for quick and dirty benchmarking
like I recently found that running on a HDD RAID that was twice as fast might have saved me half the time on the samtools mpileup command!


Using dd

Note: This method requires the command to be executed from a mounted partition on the device of interest!
First, enter a directory on the SSD with at least 1.1 GB of free space (and one that obviously gives your user wrx permissions) and write a test file to measure write speeds and to give the device something to read:
$ cd /path/to/SSD
$ dd if=/dev/zero of=tempfile bs=1M count=1024 conv=fdatasync,notrunc
1024+0 records in
1024+0 records out
w bytes (x GB) copied, y s, z MB/s
Next, clear the buffer-cache to accurately measure read speeds directly from the device:
# echo 3 > /proc/sys/vm/drop_caches
$ dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
w bytes (x GB) copied, y s, z MB/s
Now that the last file is in the buffer, repeat the command to see the speed of the buffer-cache:
$ dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
w bytes (x GB) copied, y s, z GB/s

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