I was wrong... My UNIX Guru Alex shown me the way!!! - Adding capped-memory to container "on-the-fly"

Yesterday I got a situation to perform - adding capped-memory to running container, before going for it I replied to end user asking for container downtime to perform this task, however later in late evening same day I saw Alex email in my mailbox explaining - "You don't need to reboot a Solaris container to increase its memory" and provided detailed step by step execution. I would like to take this opportunity to say thanks a lot to Alex publically... I am blessed with such a wonderful UNIX Guru...

Before going for this task my assumptions were as front - I was under impression that prctl command will do the temporary effect and will not remain across the reboot. This is what my understanding - prctl is an “on-the-fly” way to temporarily set Resource Control assignments & only after reboot modified parameter get permanent.

Then Alex replied explaining how exactly it works...

prctl, rcapadm modifies the running zone.

zonecfg defines the resource parameters of the zone when it boots.

So... To make a change dynamically you:
1) Update the zonecfg. The reason you do this is so that when rebooted it doesn't revert back to the old settings.
2) Use the prctl, rcapadm commands to modify the zone while it is online. The data you feed into prctl and rcapadm should match the changes you've made to zonecfg.

Below are the detail steps to add capped-memory to running container –

# zonecfg -z XXXXXX

zonecfg:XXXXXX> select capped-memory

zonecfg:XXXXXX:capped-memory> info

capped-memory:

physical: 1G

[swap: 2G]

[locked: 512M]

zonecfg:XXXXXX:capped-memory> set physical=2g

zonecfg:XXXXXX:capped-memory> set swap=3g

zonecfg:XXXXXX:capped-memory> info

capped-memory:

physical: 2G

[swap: 3G]

[locked: 512M]

zonecfg:XXXXXX:capped-memory> end

zonecfg:XXXXXX> exit

Now modify the zones runtime settings:

XXXXXX:/

# rcapadm -z XXXXXX -m 2048m

XXXXXX:/

# sleep 60

XXXXXX:/

# rcapstat -z 1 1

id zone nproc vm rss cap at avgat pg avgpg

9 XXXXXX - 434M 377M 2048M 0K 0K 0K 0K

10 XXXXXX - 452M 370M 2048M 0K 0K 0K 0K

14 XXXXXX - 532M 328M 2048M 0K 0K 0K 0K

XXXXXX:/

# prctl -n zone.max-swap -v 3g -t privileged -r -e deny -i zone XXXXXX

Then verify you're settings have taken effect:

XXXXXX:/

# zlogin XXXXXX

[Connected to zone 'XXXXXX' pts/9]

Last login: Wed Sep 16 06:34:27 from XXX.XXX.XX.XX

Sun Microsystems Inc. SunOS 5.10 Generic January 2005

WARNING: YOU ARE SUPERUSER on XXXXXX!!

Your shell is /usr/bin/ksh

XXXXXX:/

# top -c

load averages: 1.36, 0.67, 0.59; up 101+08:46:15 08:55:12

51 processes: 50 sleeping, 1 on cpu

CPU states: 89.6% idle, 4.4% user, 6.1% kernel, 0.0% iowait, 0.0% swap

Memory: 2048M phys mem, 177M free mem, 3072M swap, 2627M free swap

It taught me a new lesson and at the same time I am still wondering “AM I KNOWING THIS BEFORE OR I WAS JUST LOST???” SHAME ON ME, VERY DISAPPOINTING HOWEVER THIS CONCEPT IS NOW GOT HARDCODED IN MY LITTLE BRAIN….

Thanks Alex, thanks a lot.

Hope this will help someone, somewhere!