I'm sure some people will tell you not to do it this way and how it's better in jails, etc. Having said that, this is what I do and it has worked happily for me for over 6 months (and I have successfully restored files in this time).
IMHO, running rsnapshot to do backups in a jail has a host other issues like permissions problems, how you backup your freenas database that lives under /data on the USB stick, etc. This is nice and simple and it has the plus that you can use the cron feature of the FreeNAS GUI and the built in alerting, etc. The downside to this method is you have to re-add it every time you upgrade. Disk space usage here is about 1MB on the USB stick so pretty negligible.
In essence, it's as simple as temporarily mounting the root partition in read/write mode and adding the package:
Code:
mountrw /
pkg_add -r rsnapshot
On older version this was all that was needed. Since 9.2 it looks like there's some dependency issues which are always fun. In this case:
Code:
pkg_add: warning: package 'rsnapshot-1.3.1_1' requires 'rsync-3.1.0_1', but 'rsync-3.0.9_3' is installed
I solved this by removing the older version of rsync and replacing it with the newer one on the assumption that it is backwards compatible.
Code:
pkg_delete rsync-3.0.9_3 rsnapshot-1.3.1_1
pkg_add -r rsnapshot
At this point you should re-mount the root system as read-only. My preference hear is to reboot to ensure everything comes up clean.
You need to configure your rsnapshot config files now as normal. You should definitely save these somewhere else (e.g. in your pool). I have a separate hard disk under /mnt/system/ and I have a directory for storing the rsnapshot config and log files.
After this, log into the GUI and add the cronjobs on the schedule you want and as per the rsnapshot documentation. Use nice to set the priority to be lower than normal as rsync is CPU hungry and it is, after all, a backup job.
e.g.
Code:
nice -19 rsnapshot -c /mnt/system/rsnapshot/rsnapshot.conf daily
nice -19 rsnapshot -c /mnt/system/rsnapshot/rsnapshot.conf weekly
etc
As always, take a backup of your config before you do any of this. One of the great features I've been impressed with on FreeNAS is how easy it is to restore your configuration if you have backup (get a new USB stick, load FreeNAS on it, boot it and restore your config and you're away).
Good luck.