By Jeff Victor on Nov 13, 2012
One of the significant new features, and the most significant new feature releated to Oracle Solaris Zones, is casually called "Zones on Shared Storage" or simply ZOSS (rhymes with "moss"). ZOSS offers much more flexibility because you can store Solaris Zones on shared storage (surprise!) so that you can perform quick and easy migration of a zone from one system to another. This blog entry describes and demonstrates the use of ZOSS.
ZOSS provides complete support for a Solaris Zone that is stored on "shared storage." In this case, "shared storage" refers to fiber channel (FC) or iSCSI devices, although there is one lone exception that I will demonstrate soon. The primary intent is to enable you to store a zone on FC or iSCSI storage so that it can be migrated from one host computer to another much more easily and safely than in the past.
With this blog entry, I wanted to make it easy for you to try this yourself. I couldn't assume that you have a SAN available - which is a good thing, because neither do I! What could I use, instead? [There he goes, foreshadowing again... -Ed.]
Developing this entry reinforced the lesson that the solution to every lab problem is VirtualBox. Oracle VM VirtualBox (its formal name) helps here in a couple of important ways. It offers the ability to easily install multiple copies of Solaris as guests on top of any popular system (Microsoft Windows, MacOS, Solaris, Oracle Linux (and other Linuxes) etc.). It also offers the ability to create a separate virtual disk drive (VDI) that appears as a local hard disk to a guest. This virtual disk can be moved very easily from one guest to another. In other words, you can follow the steps below on a laptop or larger x86 system.
Please note that the ability to use ZOSS to store a zone on a local disk is very useful for a lab environment, but not so useful for production. I do not suggest regularly moving disk drives among computers. [Update, 2013.01.28: Apparently the previous sentence caused some confusion. I do recommend the use of Zones on Shared Storage in production environments, when appropriate storage is used. "Appropriate storage" would include SAN or iSCSI at this point. I do not recommend using ZOSS with local disks in production because doing so would require moving the disks between computers.]
In the method I describe below, that virtual hard disk will contain the zone that will be migrated among the (virtual) hosts. In production, you would use FC or iSCSI LUNs instead. The zonecfg(1M) man page details the syntax for each of the three types of devices.
Why Migrate?Why is the migration of virtual servers important? Some of the most common reasons are:
- Moving a workload to a different computer so that the original computer can be turned off for extensive maintenance.
- Moving a workload to a larger system because the workload has outgrown its original system.
- If the workload runs in an environment (such as a Solaris Zone) that is stored on shared storage, you can restore the service of the workload on an alternate computer if the original computer has failed and will not reboot.
- You can simplify lifecycle management of a workload by developing it on a laptop, migrating it to a test platform when it's ready, and finally moving it to a production system.
For ZOSS, the important new concept is named "rootzpool". You can read about it in the zonecfg(1M) man page, but here's the short version: it's the backing store (hard disk(s), or LUN(s)) that will be used to make a ZFS zpool - the zpool that will hold the zone. This zpool:
- contains the zone's Solaris content, i.e. the root file system
- does not contain any content not related to the zone
- can only be mounted by one Solaris instance at a time
Method OverviewHere is a brief list of the steps to create a zone on shared storage and migrate it. The next section shows the commands and output.
- You will need a host system with an x86 CPU (hopefully at least a couple of CPU cores), at least 2GB of RAM, and at least 25GB of free disk space. (The steps below will not actually use 25GB of disk space, but I don't want to lead you down a path that ends in a big sign that says "Your HDD is full. Good luck!")
- Configure the zone on both systems, specifying the rootzpool that both will use. The best way is to configure it on one system and then copy the output of "zonecfg export" to the other system to be used as input to zonecfg. This method reduces the chances of pilot error. (It is not necessary to configure the zone on both systems before creating it. You can configure this zone in multiple places, whenever you want, and migrate it to one of those places at any time - as long as those systems all have access to the shared storage.)
- Install the zone on one system, onto shared storage.
- Boot the zone.
- Provide system configuration information to the zone. (In the Real World(tm) you will usually automate this step.)
- Shutdown the zone.
- Detach the zone from the original system.
- Attach the zone to its new "home" system.
- Boot the zone.
DetailsThe rest of this shows the commands and output. The two hostnames are "sysA" and "sysB".
Note that each Solaris guest might use a different device name for the VDI that they share. I used the device names shown below, but you must discover the device name(s) after booting each guest. In a production environment you would also discover the device name first and then configure the zone with that name. Fortunately, you can use the command "zpool import" or "format" to discover the device on the "new" host for the zone.
The first steps create the VirtualBox guests and the shared disk drive. I describe the steps here without demonstrating them.
- Download VirtualBox and install it using a method normal for your host OS. You can read the complete instructions.
- Create two VirtualBox guests, each to run Solaris 11.1. Each will use its own VDI as its root disk.
- Install Solaris 11.1 in each guest.Install Solaris 11.1 in each guest. To install a Solaris 11.1 guest, you can either download a pre-built VirtualBox guest, and import it, or install Solaris 11.1 from the "text install" media. If you use the latter method, after booting you will not see a windowing system. To install the GUI and other important things, login and run "pkg install solaris-desktop" and take a break while it installs those important things.
- Life is usually easier if you install the VirtualBox Guest Additions because then you can copy and paste between the host and guests, etc. You can find the guest additions in the folder matching the version of VirtualBox you are using. You can also read the instructions for installing the guest additions.
- To create the zone's shared VDI in VirtualBox, you can open the storage configuration for one of the two guests, select the SATA controller, and click on the "Add Hard Disk" icon nearby. Choose "Create New Disk" and specify an appropriate path name for the file that will contain the VDI. The shared VDI must be at least 1.5 GB. Note that the guest must be stopped to do this.
- Add that VDI to the other guest - using its Storage configuration - so that each can access it while running. The steps start out the same, except that you choose "Choose Existing Disk" instead of "Create New Disk." Because the disk is configured on both of them, VirtualBox prevents you from running both guests at the same time.
- Identify device names of that VDI, in each of the guests. Solaris chooses the name based on existing devices. The names may be the same, or may be different from each other. This step is shown below as "Step 1."
AssumptionsIn the example shown below, I make these assumptions.
- The guest that will own the zone at the beginning is named sysA.
- The guest that will own the zone after the first migration is named sysB.
- On sysA, the shared disk is named /dev/dsk/c7t2d0
- On sysB, the shared disk is named /dev/dsk/c7t3d0
(Finally!) The StepsStep 1) Determine the name of the disk that will move back and forth between the systems.
root@sysA:~# format Searching for disks...done AVAILABLE DISK SELECTIONS: 0. c7t0d0Step 2) The first thing to do is partition and label the disk. The magic needed to write an EFI label is not overly complicated.
/pci@0,0/pci8086,2829@d/disk@0,0 1. c7t2d0 /pci@0,0/pci8086,2829@d/disk@2,0 Specify disk (enter its number): ^D
root@sysA:~# format -e c7t2d0 selecting c7t2d0 [disk formatted] FORMAT MENU: ... format> fdisk No fdisk table exists. The default partition for the disk is: a 100% "SOLARIS System" partition Type "y" to accept the default partition, otherwise type "n" to edit the partition table. n SELECT ONE OF THE FOLLOWING: ... Enter Selection: 1 ... G=EFI_SYS 0=Exit? f SELECT ONE... ... 6 format> label ... Specify Label type: 1 Ready to label disk, continue? y format> quit root@sysA:~# ls /dev/dsk/c7t2d0 /dev/dsk/c7t2d0Step 3) Configure zone1 on sysA.
root@sysA:~# zonecfg -z zone1 Use 'create' to begin configuring a new zone. zonecfg:zone1> create create: Using system default template 'SYSdefault' zonecfg:zone1> set zonename=zone1 zonecfg:zone1> set zonepath=/zones/zone1 zonecfg:zone1> add rootzpool zonecfg:zone1:rootzpool> add storage dev:dsk/c7t2d0 zonecfg:zone1:rootzpool> end zonecfg:zone1> exit root@sysA:~# oot@sysA:~# zonecfg -z zone1 info zonename: zone1 zonepath: /zones/zone1 brand: solaris autoboot: false bootargs: file-mac-profile: pool: limitpriv: scheduling-class: ip-type: exclusive hostid: fs-allowed: anet: ... rootzpool: storage: dev:dsk/c7t2d0Step 4) Install the zone. This step takes the most time, but you can wander off for a snack or a few laps around the gym - or both! (Just not at the same time...)
root@sysA:~# zoneadm -z zone1 install Created zone zpool: zone1_rpool Progress being logged to /var/log/zones/zoneadm.20121022T163634Z.zone1.install Image: Preparing at /zones/zone1/root. AI Manifest: /tmp/manifest.xml.RXaycg SC Profile: /usr/share/auto_install/sc_profiles/enable_sci.xml Zonename: zone1 Installation: Starting ... Creating IPS image Startup linked: 1/1 done Installing packages from: solaris origin: http://pkg.us.oracle.com/support/ DOWNLOAD PKGS FILES XFER (MB) SPEED Completed 183/183 33556/33556 222.2/222.2 2.8M/s PHASE ITEMS Installing new actions 46825/46825 Updating package state database Done Updating image state Done Creating fast lookup database Done Installation: Succeeded Note: Man pages can be obtained by installing pkg:/system/manual done. Done: Installation completed in 1696.847 seconds. Next Steps: Boot the zone, then log into the zone console (zlogin -C) to complete the configuration process. Log saved in non-global zone as /zones/zone1/root/var/log/zones/zoneadm.20121022T163634Z.zone1.installStep 5) Boot the Zone.
root@sysA:~# zoneadm -z zone1 bootStep 6) Login to zone's console to complete the specification of system information.
root@sysA:~# zlogin -C zone1Answer the usual questions and wait for a login prompt. Then you can end the console session with the usual "~." incantation.
Step 7) Shutdown the zone so it can be "moved."
root@sysA:~# zoneadm -z zone1 shutdownStep 8) Detach the zone so that the original global zone can't use it.
root@sysA:~# zoneadm list -cv ID NAME STATUS PATH BRAND IP 0 global running / solaris shared - zone1 installed /zones/zone1 solaris excl root@sysA:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 17.6G 11.2G 6.47G 63% 1.00x ONLINE - zone1_rpool 1.98G 484M 1.51G 23% 1.00x ONLINE - root@sysA:~# zoneadm -z zone1 detach Exported zone zpool: zone1_rpoolStep 9) Review the result and shutdown sysA so that sysB can use the shared disk.
root@sysA:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 17.6G 11.2G 6.47G 63% 1.00x ONLINE - root@sysA:~# zoneadm list -cv ID NAME STATUS PATH BRAND IP 0 global running / solaris shared - zone1 configured /zones/zone1 solaris excl root@sysA:~# init 0Step 10) Now boot sysB and configure a zone with the parameters shown above in Step 1. (Again, the safest method is to use "zonecfg ... export" on sysA as described in section "Method Overview" above.) The one difference is the name of the rootzpool storage device, which was shown in the list of assumptions, and which you must determine by booting sysB and using the "format" or "zpool import" command.
When that is done, you should see the output shown next. (I used the same zonename - "zone1" - in this example, but you can choose any valid zonename you want.)
root@sysB:~# zoneadm list -cv ID NAME STATUS PATH BRAND IP 0 global running / solaris shared - zone1 configured /zones/zone1 solaris excl root@sysB:~# zonecfg -z zone1 info zonename: zone1 zonepath: /zones/zone1 brand: solaris autoboot: false bootargs: file-mac-profile: pool: limitpriv: scheduling-class: ip-type: exclusive hostid: fs-allowed: anet: linkname: net0 ... rootzpool: storage: dev:dsk/c7t3d0Step 11) Attaching the zone automatically imports the zpool.
root@sysB:~# zoneadm -z zone1 attach Imported zone zpool: zone1_rpool Progress being logged to /var/log/zones/zoneadm.20121022T184034Z.zone1.attach Installing: Using existing zone boot environment Zone BE root dataset: zone1_rpool/rpool/ROOT/solaris Cache: Using /var/pkg/publisher. Updating non-global zone: Linking to image /. Processing linked: 1/1 done Updating non-global zone: Auditing packages. No updates necessary for this image. Updating non-global zone: Zone updated. Result: Attach Succeeded. Log saved in non-global zone as /zones/zone1/root/var/log/zones/zoneadm.20121022T184034Z.zone1.attach root@sysB:~# zoneadm -z zone1 boot root@sysB:~# zlogin zone1 [Connected to zone 'zone1' pts/2] Oracle Corporation SunOS 5.11 11.1 September 2012Step 12) Now let's migrate the zone back to sysA. Create a file in zone1 so we can verify it exists after we migrate the zone back, then begin migrating it back.
root@zone1:~# ls /opt root@zone1:~# touch /opt/fileA root@zone1:~# ls -l /opt/fileA -rw-r--r-- 1 root root 0 Oct 22 14:47 /opt/fileA root@zone1:~# exit logout [Connection to zone 'zone1' pts/2 closed] root@sysB:~# zoneadm -z zone1 shutdown root@sysB:~# zoneadm -z zone1 detach Exported zone zpool: zone1_rpool root@sysB:~# init 0Step 13) Back on sysA, check the status.
Oracle Corporation SunOS 5.11 11.1 September 2012 root@sysA:~# zoneadm list -cv ID NAME STATUS PATH BRAND IP 0 global running / solaris shared - zone1 configured /zones/zone1 solaris excl root@sysA:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 17.6G 11.2G 6.47G 63% 1.00x ONLINE -Step 14) Re-attach the zone back to sysA.
root@sysA:~# zoneadm -z zone1 attach Imported zone zpool: zone1_rpool Progress being logged to /var/log/zones/zoneadm.20121022T190441Z.zone1.attach Installing: Using existing zone boot environment Zone BE root dataset: zone1_rpool/rpool/ROOT/solaris Cache: Using /var/pkg/publisher. Updating non-global zone: Linking to image /. Processing linked: 1/1 done Updating non-global zone: Auditing packages. No updates necessary for this image. Updating non-global zone: Zone updated. Result: Attach Succeeded. Log saved in non-global zone as /zones/zone1/root/var/log/zones/zoneadm.20121022T190441Z.zone1.attach root@sysA:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 17.6G 11.2G 6.47G 63% 1.00x ONLINE - zone1_rpool 1.98G 491M 1.51G 24% 1.00x ONLINE - root@sysA:~# zoneadm -z zone1 boot root@sysA:~# zlogin zone1 [Connected to zone 'zone1' pts/2] Oracle Corporation SunOS 5.11 11.1 September 2012 root@zone1:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 1.98G 538M 1.46G 26% 1.00x ONLINE -Step 15) Check for the file created on sysB, earlier.
root@zone1:~# ls -l /opt total 1 -rw-r--r-- 1 root root 0 Oct 22 14:47 fileA
Next StepsHere is a brief list of some of the fun things you can try next.
- Add space to the zone by adding a second storage device to the rootzpool. Make sure that you add it to the configurations of both zones!
- Create a new zone, specifying two disks in the rootzpool when you first configure the zone. When you install that zone, or clone it from another zone, zoneadm uses those two disks to create a mirrored pool. (Three disks will result in a three-way mirror, etc.)