On Thu, Oct 15, 2015 at 12:19 PM, Paolo Aglialoro <paol...@gmail.com> wrote: > In order to minimise nand wear off, I would like to put on ramdisk (the > machine would have 2GB ram, so I believe enough also for that, but I still > can upgrade it to 4GB if needed) the parts of the file hierarchy with most > intensive system write I/O, like, for instance, /tmp and I imagine some > parts of /var. > > My questions are two: > 1. What are the dirs I should take into account to go to ramdisk? > 2. What is the correct filesystem type to put in fstab for all the entries > of point 1. in order to store them in ramdisk?
I noticed that you have not said that you would like your other filesystems to be read-only, only that you want the 'most intensive' writes to go to a ramdisk. In other words, you don't want your flash storage to be read-only, you merely want it to be read-mostly. I have done something similar myself and what I did was to make 2 mfs filesystems: /tmp and /var/log. here are my /etc/fstab entries: swap /tmp mfs rw,nodev,nosuid,-s=128M 0 0 swap /var/log mfs rw,nodev,nosuid,-s=128M,-P=/mfs/log 0 0 Note that in my setup I have an /mfs/log partition. This was originally the /var/log partition from installation, which I renamed in /etc/fstab later (after doing mkdir -p /mfs/log first). This is a 'durable' copy of /var/log meant to survive crashes, reboots or power failures. The contents of /var/log are periodically checkpointed to /mfs/log using rsync (installed from packages), via a cron job: # checkpoint log files 10 */4 * * * /usr/local/bin/rsync -aH --delete /var/log/ /mfs/log Also, I added this line to /etc/rc.shutdown to handle reboots: /usr/local/bin/rsync -aH --delete /var/log/ /mfs/log If /var/tmp isn't already a symbolic link to /tmp, do that as well to redirect another commonly written directory to ramdisk. You may also want to move cron log files from /var/cron to /var/log (or /var/log/cron if you want them to be separated from other logs). Doing so involves modifying /etc/syslog.conf and /etc/newsyslog.conf. If you do this be prepared for warnings in the nightly security check emails due to the cron log file not being found in its normal location. Leaving an empty log file in the original location is one workaround for this but I haven't tried it. A better workaround may be to modify the nightly check so that it looks for the log file in its new location. -ken
