Kernel Zones Suspend and Resume
One of the coolest Kernel Zones features is their ability to suspend and resume operations. You can use this feature either to warm migrate a kernel zone from one system to another, or to preserve your application's state while rebooting the global zone.
To be able to use this capability we have to configure the storage space where we keep the suspended zone. First check if it's configured already and then add the path to file's location.
root@solarislab:~# zonecfg -z kzone1 info suspend root@solarislab:~# zonecfg -z kzone1 zonecfg:kzone1> add suspend zonecfg:kzone1:suspend> set path=/system/zones/kzone1/suspend zonecfg:kzone1:suspend> end zonecfg:kzone1> exit root@solarislab:~# zonecfg -z kzone1 info suspend suspend: path: /system/zones/kzone1/suspend storage not specified
Good. Now we can try to suspend the kernel zone.
root@solarislab:~# zoneadm -z kzone1 suspend root@solarislab:~# zoneadm list -cv ID NAME STATUS PATH BRAND IP 0 global running / solaris shared 5 zone1 running /system/zones/zone1 solaris excl - kzone1 installed - solaris-kz excl
So what? It doesn't look very spectacular, does it? Note that kzone1
is not in any special suspended status, it's just installed, like if
we just shut it down. How can we resume it? OK, according to the zones'
lifecycle, from the installed state we can boot the zone. There is
no special resume command.
root@solarislab:~# zoneadm -z kzone1 boot root@solarislab:~# zoneadm list -cv ID NAME STATUS PATH BRAND IP 0 global running / solaris shared 5 zone1 running /system/zones/zone1 solaris excl 7 kzone1 running - solaris-kz excl
Again, nothing spectacular. We need something to see how the zone is
getting suspended and resumed. Open another terminal window, login to
the host (global zone) and then to kzone1. Inside kzone1 start a
simple script that prints out the current timestamp every second.
root@solarislab:~# zlogin -C kzone1 [Connected to zone 'kzone1' console] kzone11-3 console login: lab Password: oracle1 (not shown) Last login: Tue Aug 4 15:09:04 2015 on console Oracle Corporation SunOS 5.11 11.3 June 2015 lab@kzone11-3:~$ while true; do date ; sleep 1 ; done Wednesday, August 5, 2015 02:35:46 PM EDT Wednesday, August 5, 2015 02:35:47 PM EDT Wednesday, August 5, 2015 02:35:48 PM EDT Wednesday, August 5, 2015 02:35:49 PM EDT Wednesday, August 5, 2015 02:35:50 PM EDT Wednesday, August 5, 2015 02:35:51 PM EDT . . . (it goes on and on and on)
Now switch to the previous terminal session in the global zone and
suspend and resume kzone1 again, while watching what's going on in the
second window (in the kzone1).
root@solarislab:~# zoneadm -z kzone1 suspend root@solarislab:~# zoneadm -z kzone1 boot
In the second window at the same time:
lab@kzone1:~$ while true; do date ; sleep 1 ; done Wednesday, August 5, 2015 02:42:04 PM EDT Wednesday, August 5, 2015 02:42:05 PM EDT Wednesday, August 5, 2015 02:42:06 PM EDT Wednesday, August 5, 2015 02:42:07 PM EDT Wednesday, August 5, 2015 02:42:08 PM EDT Wednesday, August 5, 2015 02:42:09 PM EDT Wednesday, August 5, 2015 02:42:10 PM EDT [NOTICE: Zone suspending] OSQ: suspending devices... suspending ORCL,kz-zvterm@0 (aka zvterm) suspending ORCL,kz-zvblk@0 (aka zvblk) suspending zvcntrl@0 suspending zvnet@0 suspending zvsdir@0 suspending ORCL,kz-extenders@ff (aka zvnex) [NOTICE: Zone halted] [NOTICE: Zone resuming] resuming ORCL,kz-extenders@ff (aka zvnex) resuming zvsdir@0 resuming zvnet@0 resuming zvcntrl@0 resuming ORCL,kz-zvblk@0 (aka zvblk) resuming ORCL,kz-zvterm@0 (aka zvterm) OSQ: resume devices completed Wednesday, August 5, 2015 02:42:11 PM EDT Wednesday, August 5, 2015 02:42:12 PM EDT Wednesday, August 5, 2015 02:42:13 PM EDT Wednesday, August 5, 2015 02:42:14 PM EDT Wednesday, August 5, 2015 02:42:15 PM EDT Wednesday, August 5, 2015 02:42:16 PM EDT ^C
This is really interesting! Now we see that the zone has been suspended and then resumed and continued the script from the point where it was left. That was definitely not possible with traditional non-global zones and now we can do this with kernel zones. Think about it: how can you use it with your applications? What might be a good test to see if they are really suspended and resumed?