6.4.2. Configuring the I/O Scheduler for Red Hat Enterprise Linux 7

For a Red Hat Enterprise Linux 7 guest, changes to the I/O scheduler can be made persistent through boot by adding the following elevator to /etc/grub2.cfg, as in the following example:
# vi /etc/grub2.cfg

linux16 /vmlinuz-kernel-version root=/dev/mapper/vg0-lv0 ro  rd.lvm.lv=vg0/lv0 vconsole.keymap=us vconsole.font=latarcyrheb-sun16 rhgb quiet elevator=deadline
initrd16 /initramfs-kernel-version.img