Performing Multiple Installations with an Alternate Root

The Communications Suite installer allows multiple installations of the same product version on the same machine or Solaris zone by using different INSTALLROOTS. By using the altroot option of the commpkg install command, you can create multiple INSTALLROOTS on the same machine.

This document contains the following sections:

Using Multiple Installations in a Side-by-Side Upgrade Scenario

The multiple-installation feature lets you perform side-by-side upgrades of some Communications Suite products.

In a side-by-side upgrade, the existing software on the host can continue to run while you install the new versions of the products on an alternate root on the same host. This approach minimizes downtime, so that end users can have continuous (or near-continuous) access to their email, calendars, and so on.

Summary of Side-by-Side Upgrade Steps

In a side-by-side upgrade scenario, you perform the following tasks:

1. Install the new Communications Suite software on the same host as the earlier versions. You can use the commpkg install commands shown in To Install a Communications Suite Product in an Alternate Root.
   
   
2. Configure the new software. Run the configuration script for the product.
   
   
3. Migrate data to the new directories under the alternate root's INSTALLROOT.
   
   
4. Configure alternate ports for the new installation under the alternate root. Alternatively, configure the host as a multi-home. For details, see Running Multiple Installations of the Same Product on One Host - Conflicting Ports.
   
   
5. Test the new software.
   
   
6. Switch end users to the new environment.

For more information about the side-by-side upgrade scenario, see Using the Side-by-Side Strategy to Upgrade Messaging Server.

To Install a Communications Suite Product in an Alternate Root

Install the product in the alternate root with the —altroot option:

1. Install OS patches and Shared Components in the default INSTALLROOT. See To Begin Installation.
   
   To install only the shared components, you can run commpkg install without --altroot and select the product you want to install. You select a product by entering the number displayed next to it in the install list. Add a ~ (tilde) in front of the product number.
   
   For example, if you plan to install Messaging Server in the alternate root, you select ~3 during the default installation. This tells the installer to install the dependencies but not the product itself.
   
   

   Note OS patches are always applied in the default INSTALLROOT, never in the alternate root.

   
   
   

2. Install the product in the altroot, as in the following example:
   
   

   commpkg install --altroot --installroot /opt/sun/comms2
   

   
   
   Be sure to use —installroot with —altroot to specify the alternate root.
   
   You can also avoid installing the shared components in the altroot by using the --excludeSC option, as in the following example:
   
   

   commpkg install --excludeSC --altroot --installroot /opt/sun/comms2
   

   
   
   You may create as many alternate roots as you like. However, you should manually keep track of all the alternate roots you have created.

Understanding INSTALLROOT and Altroot

The following concepts define an altroot:

• An altroot is an alternate root directory.
• The altroot is used for multiple installations of Communications Suite products on the same host.
• The default root is the standard root directory, which can be indicated with a /.
• An altroot implies the existence of a default root.

The following concepts define an INSTALLROOT:

• An INSTALLROOT is the top-level installation path for the Communications Suite products and shared components.
• There is an INSTALLROOT (an installation path) for each instance of the installed products. That is, if your system has a default root and an altroot, the default root has one INSTALLROOT, and the altroot must have a different INSTALLROOT.

Now let's put them together:

• You define an altroot by specifying its INSTALLROOT and using the --altroot option with the commpkg install command.

What's the Default?

If you use the default root and the default INSTALLROOT, the commpkg install command installs products under the following top-level directory:

/opt/sun/comms/

An Example

Now suppose you want to install one instance of the products in /opt/sun/mycompany/comms/; and another instance of the same products in /opt/sun/mycompany/comms2/. You would use the following commands:

For the default root:

commpkg install --installroot /opt/sun/mycompany/comms/

For the altroot:

commpkg install --altroot --installroot /opt/sun/mycompany/comms2/

Running Multiple Installations of the Same Product on One Host: Conflicting Ports

By default, after you initially configure the product on alternate roots, the ports used by the different product installations are the same and thus conflict with each other.

This is not a problem if you install multiple installations of the same product on the same host but only intend to have one instance running at one time. For example, you may perform a side-by-side upgrade scenario in which you plan to stop the old instance before you start the new instance.

However, you may plan to test the new instance while the old instance is still running (and supporting end users). In this scenario, the ports are used simultaneously.

There are two ways to resolve this conflict:

• Configure individual ports
• Use a multi-home configuration

These approaches are described in the following sections.

Configuring Individual Ports

See Configuring Individual Ports for Multiple Installations of the Same Product.

Configuring a Host to Be Multi-Homed

See Configuring a Host to be Multi-Homed.