Sparse Root Zones

In the Solaris 10 release, non-global zones that have inherit-pkg-dir resources are called sparse root zones.

The sparse root zone model optimizes the sharing of objects in the following ways:

• Only a subset of the packages installed in the global zone are installed directly into the non-global zone.

• Read-only loopback file systems, identified as inherit-pkg-dir resources, are used to gain access to other files.

In this model, all packages appear to be installed in the non-global zone. Packages that do not deliver content into read-only loopback mount file systems are fully installed. There is no need to install content delivered into read-only loopback mounted file systems since that content is inherited (and visible) from the global zone.

• As a general guideline, a zone requires about 100 megabytes of free disk space per zone when the global zone has been installed with all of the standard Solaris packages.

• By default, any additional packages installed in the global zone also populate the non-global zones. The amount of disk space required might be increased accordingly, depending on whether the additional packages deliver files that reside in the inherit-pkg-dir resource space.

An additional 40 megabytes of RAM per zone are suggested, but not required on a machine with sufficient swap space.