Linux I/O Scheduler

Selecting a Linux I/O Scheduler
How do I change I/O scheduler?

cat /sys/block/sda/queue/scheduler
echo noop > /sys/block/sda/queue/scheduler

In /etc/default/grub change

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash elevator=noop"

Then run

sudo update-grub2

and restart.