Multiple Boot Environments

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Revision as of 09:34, 10 July 2012 by Drulavigne (Talk | contribs)

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(Sorry for the inconvenience)

Beginning with version 9.1, PC-BSD supports multiple boot environments on systems that were formatted with ZFS during installation. In 9.1, this feature is configured from the command line. Version 9.2 will provide a graphical interface for managing boot environments (BEs).

Multiple boot environments is a feature originally created by Solaris. It allows you to create a BE, which is a bootable, point-in-time snapshot of the ZFS filesystem. By booting into a snapshot, you return to that point in time in the filesystem. For example, you could create a BE before upgrading, allowing you to boot either into the newly upgraded system or into the snapshot of the system before it was upgraded. Alternately, you could create a snapshot before installing and configuring some software that you wish to test. Once your test is finished, you could boot into what the system looked like before the test.

BE's are managed withe the beadm command which must be run as the superuser. The following example creates a BE of the ZFS pool named beforeupgrade.

beadm create beforeupgrade 
Created successfully

To view the BEs, use the list command

beadm list
BE            Active Mountpoint Space Policy Created
default       NR     /          6.05G static 2012-07-09 05:06
beforeupgrade -      -             1K static 2012-07-10 12:25

The possible flags in the Active field are as follows:

  • R: active on reboot
  • N: active now
  • NR: active now and active on reboot
  • -: inactive

In this example, the ZFS pool is the default BE, is active now and at next reboot, and is mounted. The newly created beforeupgrade BE exists, but is inactive. To activate the new BE:

beadm activate beforeupgrade
Activated successfully
beadm list
BE            Active Mountpoint Space Policy Created
default       N      /          64.5K static 2012-07-09 05:06
beforeupgrade R      -          6.05G static 2012-07-10 12:25


References