Solaris Zone(Containers) – Interview Questions

Here I would like to share interview questions regarding Solaris zones which will be normally asked for L2 level candidates in Solaris interviews. Now a days virtualization plays very important role in infrastructure market to reduce the data center space,power and utilizing hardware potentially. The virtualization goal is that utilizing the hardware without scarifying the application performance and reducing  the operational cost. 
We will see some of the interview questions and its answer here.Stay tuned.

Q 1.What are virtualization technologies  are supported by oracle ?
A.  Please go through the oracle virtualization technologies to understand various oracle virtualization products.

Q 2. What is difference between global zone and non-global zone ? 
A. Base Solaris operating system is called global zone.(Directly installed on physical hardware).Solaris operating system which are hosted by global zone is called Non-global zones or local zone.

Q 3. How to find the global zone name from Non-global zones ?
A. There is no way to find the global zone name from Non-global zone.Oracle made this one intentionally for security reasons. However you can few tricks to find the global zone name.here.

Q 4.What type of Non-global zones in Solaris 10 ?
A. There are three type of non-global zones in Solaris 10.
     1. Whole root zone.
     2. Sparse root zone.
     3. Branded zone.

Q 5.What is the difference between whole root zone and sparse root zone ?
A. Whole root zones have all their binaries of their own zone root filesystem,while sparse root zones mount /usr,/lib,/platform,/sbin from the global zone.

Q 6.How to identify  which is whole root zone and sparse root zone ?
A. Using zonecfg -z zone_name you can determine whether its a whole root zone or sparse root zone.
If its sparse root zone,you can see inherit packages of /usr,/sbin/,/platform,/lib where as in whole root zone,you won;t see these.

# zonecfg -z zarena info
zonename: zarena
zonepath: /zoravol1
brand: native
autoboot: false
bootargs:
pool:
limitpriv:
scheduling-class:
ip-type: shared
hostid:
inherit-pkg-dir:
        dir: /lib
inherit-pkg-dir:
        dir: /platform
inherit-pkg-dir:
        dir: /sbin
inherit-pkg-dir:
        dir: /usr

Q 7. How do you login to zone’s OS console ?
A. From global zone,use “zlogin -C zone_name”

Q 8.Is it possible to assign ZFS/ZPOOL to local zone ?
A.  Yes.Its possible to assign ZPOOL/ZFS to local zone.

Q 9.Is it possible to assign VXFS filesystem to local zone ?
A. Yes.We can mount VXFS filesystem on non-global zone

Q 10.Is it possible to put resource control on Solaris Non-global zone ? what are the resources can be control ?
A. Yes.We can restrict memory,swap,cpu for local zone.

Q 11.Is it possible to modify the resource value dynamically ? If yes How to perform the dynamic resource control in zones? 
A. We can modify the resource values dynamically using rcapadm and pooladm. Step by step guide can be found here.

Q 12.How to Perform resource capping ? 
A. Resource capping can be done using zonecfg.

Q 13.How to patch the Solaris global zone with vxfs root local zones ?
A. You can look at this article.

Q 14.Is it possible to add zone as resource in VCS ?
A. Yes. You can add zone as resource in VCS.

Q 15.How to boot local zone in single user mode ?
A. using “zoneadm -z boot -s” command you can boot zone in single user mode.

Q 16.How to prevent non-global zone coredumps from global zone?
A. By modifying coreadm parameter,you can stop the Non-global zone coredumps in global zone.

Q 17. Is it possible to add new IP address on Non-global zone on fly ? If yes how to do that?
A. Yes.we can plumb new IP on zones using ifconfig command. Here is the step by step guide.

Q 18.How to get zone wise process list using prstat command ?
A. Use prstat -Z to get zone wise statistics.

Q 19.What is Branded zone ?
A. Branded zone is used to install older version of Solaris or Linux in Solaris 10 global zone. 

• Brand ‘solaris8’ provides a Solaris 8 environment on a Solaris 10 system.
• Brand ‘solaris9’ provides a Solaris 9 environment on a Solaris 10 system.
• ‘lx’ provides a Red Hat Enterprise Linux 3 environment on a Solaris 10 system
• ‘s10brand’ provides a Solaris 10 environment on an OpenSolaris or Oracle Solaris 11 system

Q 20.How to boot local zone ?
A. Using “zoneadm -z zone_name boot” from global zone,we can boot non-global zone.

Q 21.How to halt the local zone ?
A. Using “zoneadm -z zone_name halt” from global zone,we can halt the local zone.

Q 22.What are the different type of states in non-global zone ?
A. 
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Q 23.Where the zone’s configuration file resides ?
A. Zone configuration can be found in /etc/zones/zone_name.xml.

Q 24.Which configuration file will be having zone’s current state ?
A. All zone;s state will be written in global zone’s  /etc/zones/index.xml .

Q 25. Which zone will be having space optimized root filesystem ?
A. Sparse root zone. Most of the binaries will be mounted in sparse root using lofs.

Q 26.How many Solaris zones can be create in on global zone?
A. Maximum of 8191 local zones can be created within a single operating system instance.

Hope now you can able to answer any questions related Solaris zones.If you have any questions regarding zones,please comment it.

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