Migrating a Zone to a Different Machine on Solaris 10

Zones are one of the best features in Solaris 10 -- they're so lightweight that you can use them at almost no cost in performance. Today, I ran across a situation where one of my zones needed more RAM, and the box it was on didn't have it. Read on for how to migrate a Solaris Zone to a different machine, and an important update to Solaris 10/08 that makes the process so much easier.

The initial steps in migrating a zone are very similar. First, you need to halt the zone:

zoneadm -z myzone halt

Next, you need to detach it from it's non-global zone:

zoneadm -z my-zone detach

Now, you need to copy the zone files over to machine B. You can use rsync + ssh, tar + ssh, tar + ftp, cpio, or any other mechanism. If you have your zone installed in /apps/zones, then the following should do the trick:

root@hostA # cd /apps/zones; tar -cf myzone.tar myzone
root@hostA # scp myzone.tar someuser@hostB:/var/tmp/ && rm myzone.tar
# ssh over to hostB, and become root 
root@hostB # cd /apps/zones/ && tar -xf /var/tmp/myzone.tar && rm /var/tmp/myzone.tar
root@hostB # zonecfg -z my-zone
my-zone: No such zone configured
Use 'create' to begin configuring a new zone.
zonecfg:my-zone> create -a /apps/zones/my-zone
zonecfg:my-zone> commit
zonecfg:my-zone> exit

As you can see, the process of moving a zone isn't too difficult, but the sticking point is when the global zone on machine A has different software and patches than machine B. Since a non-global zone's inherit files and packages from the global zone, things can get messy. Up until Solaris 10/08, getting things straightened out was an exercise left up to the sysadmin, and it often times was no small task. If you're on a release prior to 10/08, and there's a lot of difference between Machine A & B, then you have your work cut out for you. Try this (running this on 10/08 or newer doesn't hurt anything, and it allows you to "preview" changes):

root@gaia /apps# zoneadm -z sstg attach
These packages installed on this system were not installed on the source system:
	SUNWi15cs (2.0,REV=2004.08.23.14.43)
	SUNWi1cs (2.0,REV=2004.08.12.10.14)
	SUNWlocaledefsrc (11.10.0,REV=2004.08.12.18.18)
	SUNWnamdt (1.0,REV=2004.08.12.10.18)
	SUNWnamos (11.10.0,REV=2003.12.08.12.08)
	SUNWnamow (1.0,REV=2004.03.03.14.07)
	SUNWplow (1.0,REV=2004.08.12.10.19)
	SUNWplow1 (1.0,REV=2004.11.10.13.49)
	SUNWpsvrr (5.0,REV=2005.05.13.16.32)
	SUNWpsvru (5.0,REV=2005.05.13.16.32)
	SUNWtcatr (11.10.0,REV=2005.01.08.05.16)
These patches installed on the source system are inconsistent with this system:
	118666: version mismatch
		(18) (20)
	118667: version mismatch
		(18) (19)
	118683: version mismatch
		(02) (03)
	118718: version mismatch
		(01) (02)
	118777: version mismatch
		(13) (14)
	118959: version mismatch
		(03) (04)
	119059: version mismatch
		(46) (47)
	119090: version mismatch
		(31) (32)
	119213: version mismatch
		(18) (19)
	119254: version mismatch
		(65) (66)
	119278: version mismatch
		(25) (27)
	119280: version mismatch
		(19) (20)
	119315: version mismatch
		(15) (16)
	119470: version mismatch
		(15) (16)
	119538: version mismatch
		(18) (19)
	119757: version mismatch
		(14) (15)
	119963: version mismatch
		(12) (15)
	120272: version mismatch
		(23) (24)
	120410: version mismatch
		(30) (31)
	120753: version mismatch
		(05) (07)
	120812: version mismatch
		(29) (30)
	121081: version mismatch
		(06) (08)
	121104: version mismatch
		(06) (07)
	122212: version mismatch
		(32) (33)
	122259: version mismatch
		(01) (02)
	122261: version mismatch
		(01) (02)
	122675: version mismatch
		(02) (03)
	122911: version mismatch
		(15) (16)
	123590: version mismatch
		(09) (10)
	123893: version mismatch
		(05) (15)
	123938: version mismatch
		(01) (02)
	124149: version mismatch
		(14) (15)
	125172: version mismatch
		(01) (02)
	125332: version mismatch
		(05) (06)
	125533: version mismatch
		(10) (11)
	125555: version mismatch
		(02) (04)
	125719: version mismatch
		(17) (20)
	125952: version mismatch
		(18) (19)
	126530: version mismatch
		(01) (02)
	126655: version mismatch
		(01) (02)
	127976: version mismatch
		(04) (05)
	136998: version mismatch
		(05) (06)
	137000: version mismatch
		(03) (04)
	137034: version mismatch
		(01) (02)
	137080: version mismatch
		(02) (03)
	138174: version mismatch
		(01) (02)
	138322: version mismatch
		(02) (03)
	138822: version mismatch
		(02) (04)
	138826: version mismatch
		(02) (04)
	138874: version mismatch
		(01) (03)
	139099: version mismatch
		(01) (02)
	139606: version mismatch
		(01) (02)
	139928: version mismatch
		(01) (02)
	139966: version mismatch
		(01) (02)
	139974: version mismatch
		(02) (03)
	139977: version mismatch
		(03) (04)
	140074: version mismatch
		(05) (08)
	140171: version mismatch
		(01) (02)
	140391: version mismatch
		(02) (03)
	140397: version mismatch
		(06) (08)
These patches installed on this system were not installed on the source system:
	119397-09
	119788-09
	122130-04
	125060-05
	136708-01
	140589-01
	140916-01
	140917-01
	140919-01
	140921-01
	141414-01
	141686-01
	141688-01
	141690-01
	141692-01
	141694-01
	141715-01
	141717-01
	141719-01
	141721-01
	141726-01
	141729-01
	141731-01
	141733-01
	141736-01
	141738-01
	141740-01
	141742-01
	141743-01
	141765-01
	141767-01
	141773-01
	141775-01
	141781-01

WOW. That's a lot of cleanup. It's no wonder Sun was compelled to add the update flag. Here's how to save yourself some hair:

root@hostB /apps# zoneadm -z my-zone attach -u
Getting the list of files to remove
Removing 935 files
Remove 237 of 237 packagess
Installing 1903 files
Add 248 of 248 packages
Updating editable files
The file  within the zone contains a log of the zone update.

At this point, you're good to 'boot' the zone on HostB. Thanks to Sun's update feature, moving my resource-starved zone to a larger server was a painless ordeal