Linux, Ramdisk.
/usr/sbin/start-raid1-ramdisk, running this script on a 4k xfs root file system should show something like: # /usr/sbin/start-raid1-ramdisk Volume group "ol" is already consistent. RAID1 ramdisk: intending to use 10276864 K of memory for facilitation of [ / ] Physical volume "/dev/zram0"