Playing around with Opensol...

ZFS snapshot based boot environments

I´ve started with the Release Candidate 2

jmoekamp@glamdring:~# cat /etc/release 
                       Open Solaris 2008.05 snv_86_rc2 X86
           Copyright 2008 Sun Microsystems, Inc.  All Rights Reserved.
                        Use is subject to license terms.
                             Assembled 21 April 2008

Okay, now i´ve updated the package list and started the update of my installation.

jmoekamp@glamdring:~# pkg refresh
jmoekamp@glamdring:~# pkg image-update
DOWNLOAD                                    PKGS       FILES     XFER (MB)
Completed                                    4/4         3/3     1.24/1.24 

PHASE                                        ACTIONS
Update Phase                                   13/13 
A clone of opensolaris exists and has been updated and activated. 
On next boot the Boot Environment opensolaris-1 will be mounted
on '/'. Reboot when ready to switch to this updated BE.

A really neat feature of the package manager is the automatic generation of an zfs-snapshot based boot environment:

jmoekamp@glamdring:~# zfs list
NAME                                                        USED  AVAIL  REFER  MOUNTPOINT
rpool                                                      2.37G   142G  56.5K  /rpool
rpool@install                                              18.5K      -    55K  -
rpool/ROOT                                                 2.28G   142G    18K  /rpool/ROOT
rpool/ROOT@install                                             0      -    18K  -
rpool/ROOT/opensolaris                                      122K   142G  2.23G  legacy
rpool/ROOT/opensolaris-1                                   2.28G   142G  2.23G  legacy
rpool/ROOT/opensolaris-1@install                           4.66M      -  2.22G  -
rpool/ROOT/opensolaris-1@static:-:2008-04-29-17:59:13       562K      -  2.23G  -
rpool/ROOT/opensolaris-1/opt                               3.60M   142G  3.60M  /opt
rpool/ROOT/opensolaris-1/opt@install                           0      -  3.60M  -
rpool/ROOT/opensolaris-1/opt@static:-:2008-04-29-17:59:13      0      -  3.60M  -
rpool/ROOT/opensolaris/opt                                     0   142G  3.60M  /opt
rpool/export                                               85.8M   142G    19K  /export
rpool/export@install                                           0      -    19K  -
rpool/export/home                                          85.8M   142G  85.8M  /export/home
rpool/export/home@install                                    18K      -    21K  -

The update automatically triggers the creation of a new boot-environment and the integration of this boot-environment to GRUB. Next time when you start your system, it will start with this boot environment.

jmoekamp@glamdring:/# beadm list
BE            Active Active on Mountpoint Space 
Name                 reboot               Used 
----          ------ --------- ---------- -----
opensolaris-1 yes    yes       legacy     2.29G
opensolaris   no     no        -          57.37M

I rebooted here, and after the reboot the operating system came up as a Release Candidate 2a system:

jmoekamp@glamdring:~$ cat /etc/release 
                       Open Solaris 2008.05 snv_86_rc2a X86
           Copyright 2008 Sun Microsystems, Inc.  All Rights Reserved.
                        Use is subject to license terms.
                             Assembled 23 April 2008

Nice ... switching to the old environment is really easy

jmoekamp@glamdring:/# beadm activate opensolaris

Now we can reboot again. Et voila, after the reboot you are back in your Release Candidate 2 operating system.

jmoekamp@glamdring:~# cat /etc/release 
                       Open Solaris 2008.05 snv_86_rc2 X86
           Copyright 2008 Sun Microsystems, Inc.  All Rights Reserved.
                        Use is subject to license terms.
                             Assembled 21 April 2008

When you look into the list of boot environments, you will see that the both environment swapped their roles.

jmoekamp@glamdring:~# beadm list
BE            Active Active on Mountpoint Space 
Name                 reboot               Used  
----          ------ --------- ---------- ----- 
opensolaris-1 no     no        -          63.57M
opensolaris   yes    yes       legacy     2.30G

Of course, you can jump back to the newer installation again.

jmoekamp@glamdring:~# beadm activate opensolaris-1

Reboot the system and afterwards you have your Release Candidate 2a operating system online again.

jmoekamp@glamdring:~$ cat /etc/release 
                       Open Solaris 2008.05 snv_86_rc2a X86
           Copyright 2008 Sun Microsystems, Inc.  All Rights Reserved.
                        Use is subject to license terms.
                             Assembled 23 April 2008

A nice side effect of snapshot based boot environments

Every now and then even a experienced admin tends to do really dumb errors. Like me .... i´ve accidentally deleted the /etc/hosts:

jmoekamp@glamdring:/# echo "192.168.1.xxx fileserver.internal" > /etc/hosts

Fsck! But then i thought: "The system makes snapshots when upgrading packages". Okay, snapshots are accessible by using the .zfs directory in the root of the filesystem. So i just had to go into a snapshot directory and gather an older /etc/hosts version.

jmoekamp@glamdring:/# cd .zfs
jmoekamp@glamdring:/.zfs# ls
snapshot
jmoekamp@glamdring:/.zfs# cd snapshot/
jmoekamp@glamdring:/.zfs/snapshot# ls
install  static:-:2008-04-29-17:59:13
jmoekamp@glamdring:/.zfs/snapshot# cd static\:-\:2008-04-29-17\:59\:13/
jmoekamp@glamdring:/.zfs/snapshot/static:-:2008-04-29-17:59:13# cd etc/
jmoekamp@glamdring:/.zfs/snapshot/static:-:2008-04-29-17:59:13/etc# cat hosts 
# CDDL HEADER START
#
[..]
#
::1		localhost
127.0.0.1	glamdring glamdring.local localhost loghost
jmoekamp@glamdring:/.zfs/snapshot/static:-:2008-04-29-17:59:13/etc# cp hosts /etc/hosts 
jmoekamp@glamdring:/.zfs/snapshot/static:-:2008-04-29-17:59:13/etc# cd /

And now i was able to add the hostname in a correct way without deleting it:

jmoekamp@glamdring:/# echo "192.168.1.xxx fileserver.internal" >> /etc/hosts