Booting alternate device using reboot command

The other day after mirroring root disk I needed to test new devalias I made for backup root disk to see if the system would boot from it. Since my servers are headless and I was not “inclined” to console into it I wondered if it was somehow possible to reboot the system and have it boot from alternate boot device.

Knowing it’s possible to do reboot – -rv and such, I fired up the reboot man page. It turns out one can reboot system using:

root@ultra# reboot -- backup_root

This will cause the system too boot from backup_root device alias. Of course, the device alias had to be valid, which it was. Otherwise, I would end up forcing myself to console to the server.

You can also pass in the boot command some flags. For example to boot system from backup_root with -rv boot flags you would do:

root@ultra# reboot -- backup_root -rv