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 /sadm/system/logs/update_log> 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