# MacOS – Can I put /tmp and /var/log in a ramdisk on OS X

macmacosramdisktmpfs

For non-critical Linux systems, I often move things like /tmp and /var/log to tmpfs to save on some disk writing. I've been doing this for a year or so and if I ever need the logs across reboots, I just comment out a line in /etc/fstab and then start debugging.

In any case, I would like to do the same thing on OS X. I've seen posts on creating a ramdisk for OS X, but I'm looking for a more permanent solution that works on every boot. I always want /tmp and /var/log mounted in a ramdisk, with the ability to turn that off with a bit of command-line editing in vi if I have to.

#!/bin/bash
ramfs_size_sectors=$((${ramfs_size_mb}*1024*1024/512))
ramdisk_dev=hdid -nomount ram://${ramfs_size_sectors} newfs_hfs -v 'Volatile'${ramdisk_dev}
mkdir -p ${mount_point} mount -o noatime -t hfs${ramdisk_dev} ${mount_point} echo "remove with:" echo "umount${mount_point}"