Equalzing Full Zones & Shared Zones

If you have the need for a full zones one where nothing is inherited from the global filesystem so you are free to change/patch any of the core files in the zone besides the kernel that is not part of the zone and is shared with all zones. A typical zone with inherited filesystems uses about 100MB of disk space; you can reduce it to 50MB using a compressed ZFS filesystem. The full zone on the other hand uses a lot more disk space, in my example it uses 3.43 GB each, even compressed. but if you use the power and features of ZFS you can reduce even full zones to just a few hundred kilobytes, Your mileage may vary since I have more than a base configuration on the box I used to test. So lets look at what happened when cloned using the power of ZFS.

Setup the ZFS filesystem

zfs create data/zone_test
zfs set compression=on data/zone_test

Create a Full Zone

zonecfg:fz_1> export
create -b
set zonepath=/data/zone_test/fz_1
set autoboot=false
add net
set address=192.168.1.110
set physical=hme0
end
zonecfg:fz_1>

Install the Zone

enterprise:data# time zoneadm -z fz_1  install
A ZFS file system has been created for this zone.
Preparing to install zone .
Creating list of files to copy from the global zone.
Copying <154355> files to the zone.
Initializing zone product registry.
Determining zone package initialization order.
Preparing to initialize <1261> packages on the zone.
Initialized <1261> packages on zone.
Zone  is initialized.
Installation of these packages generated errors: 
The file  contains a log of the zone installation.

real    48m39.784s
user    11m14.189s
sys     23m0.554s
enterprise:data#

Wow it takes a while to create a full zone.

now let’s get ready to clone the zone.
Configure our second zone using the configuration from the first zone

enterprise:data# zonecfg -z fz_1 export|sed -e 's/fz_1/fz_3/'|zonecfg -z fz_3
fz_3: No such zone configured
Use 'create' to begin configuring a new zone.
enterprise:data#

Clone the first filesystem and create a second.

time zoneadm -z fz_2 clone fz_1
WARNING: network address '192.168.1.110' is configured in both zones.
Cloning snapshot data/zone_test/fz_1@SUNWzone1
Instead of copying, a ZFS clone has been created for this zone.

real    0m9.954s
user    0m0.314s
sys     0m0.934s

9.9 seconds a much faster way to make zones.

Let’s compare with a standard zone.

enterprise:data# time zoneadm -z pz_1 install
A ZFS file system has been created for this zone.
Preparing to install zone .
Creating list of files to copy from the global zone.
Copying <15748> files to the zone.
Initializing zone product registry.
Determining zone package initialization order.
Preparing to initialize <1261> packages on the zone.
Initialized <1261> packages on zone.
Zone  is initialized.
Installation of these packages generated warnings: 
The file  contains a log of the zone installation.

real    27m51.243s
user    7m58.771s
sys     14m58.229s
enterprise:data#

enterprise:data# time zoneadm -z pz_3 clone pz_1
WARNING: network address '192.168.1.192' is configured in both zones.
Cloning snapshot data/zone_test/pz_1@SUNWzone1
Instead of copying, a ZFS clone has been created for this zone.

real    0m14.031s
user    0m2.060s
sys     0m1.039s
enterprise:data# zfs list data/zone_test_pz_3
cannot open 'data/zone_test_pz_3': no such filesystem

Diskspace used

enterprise:data# zfs list -r data/zone_test/
cannot open 'data/zone_test/': invalid filesystem name
enterprise:data# zfs list -r data/zone_test
NAME                   USED  AVAIL  REFER  MOUNTPOINT
data/zone_test        3.72G   815M    57K  /data/zone_test
data/zone_test/fz_1   3.44G   815M  3.43G  /data/zone_test/fz_1
data/zone_test/fz_1@SUNWzone1  18.4M      -  3.43G  -
data/zone_test/fz_2    143K   815M  3.43G  /data/zone_test/fz_2
data/zone_test/pz_1    283M   815M   283M  /data/zone_test/pz_1
data/zone_test/pz_1@SUNWzone1   145K      -   283M  -
data/zone_test/pz_3    130K   815M   283M  /data/zone_test/pz_3
enterprise:data#

[fz == full zone] [pz=shared zone]

Thanks to ZFS, compression and cloning, you can see that the use of disk per zone is less than 150K, 143K for the full zone, and 130K for the shared zone. Of course changing files in the core install will increase the amount of disk space used on full zones, but you can’t have everything. ZFS also equalizes the time to create the zones, reduces it from 45 minutes to less than 10 seconds even for full zones.