Mirrored vdevs are great for performance and it is quite straight-forward to add a mirrored vdev to an existing pool (presumably one with one or more similar vdevs already): zpool add [poolname] mirror [device01] [device02] [device03] If it’s a two-way mirror you will only have two devices in the above. An example…
Sometimes you may with to add files to an existing backup; if you issue a command like: tar -cvf /dev/st0 backupfiles …and the tape is not already set to the end of the previous archive you will over-write any data from the position on the tape. Use the “eom” command to move…
To add an existing user to a second group, use the following command: sudo usermod -a -G [group] [user] e.g.: sudo usermod -a -G geeks bob This will add the user bob to the group geeks.