Technical Memo: PAN Configuration Backup Strategies





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PAN CONFIGURATION BACKUP STRATEGIES

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Abstract

Discusses contents of various directories comprising GrayMatter Software's ScriptServer® PAN Printing System in the context of planning a backup strategy.

How the ScriptServer® PAN Printing System's Directories are Organized

PAN is a complex product, with numerous components and configuration items.When PAN is installed, it is typically installed under a single directory tree (in fact it is typically installed under its own account). For the most part, this categorization is reflected in the directory structure utilized by PAN:

NOTE: The information in the following table is a useful generalization within the context of this discussion, but it should not be construed as final, absolute, authoritative fact.

category	components/items in category	directory	notes
static components/items	some cgis/programs web interface collaterals		These are static and could be restored from the original installation media
configured components	some cgis/programs system configuration items	`bin/ sbin/` server`/cgi-bin` apache`/httpd.conf`	Certain programs need to be edited when the PAN is configured so that they can talk to each other without relying on external resources. Additionally, you may have created a special account to install PAN under, and you may have modified your web server configuration to allow PAN CGIs to execute. server is the directory where web collaterals are published, also referred to within PAN as the Virtual Path. It is typically `web` or `public_html`. `httpd.conf` is typically modified as described in this technical memo to allow the PAN CGIs to run.
site-specific resources and assets	forms, queues, resources, images, fonts, etc.	`conf/` resources/	Resources used for output management and job processing. These are site-specific, and may even be queue-specific (the late binding technique used by PAN means that different resource instances may be utilized by different queues). `resources/` contains assets such as images and fonts which cannot conveniently be contained within a configuration file. `conf/` contains several files which collectively describe the resources and assets.
dynamic/temporary data	log files, spooled jobs, etc.	`var/`	The lifecycle of these transitory items is tied to the actual processing of queued jobs. Included here are log files and spool files.

Implications for Backup/Restore and Recovery Planning

Different reasons for backing up

Different sites may have different reasons for making backups:

"undo": You want to revert to the configuration state prior to the modification of one or more assets.
configuration: You want to make sure all assets can be restored in the event system recovery is required.
installation: You want to be able to restore a complete installation in the event system recovery is requred.
snapshot: You want to make a snapshot of the state of a system, including all jobs, etc.

Some suggestions

Only you can determine the appropriate strategies for your situation (taking into account all risks and potential impacts), but we do make the following observations:

In all cases, you will want to back up the conf/ and resources/ directories. For undo, these site-specific resources and assets may be sufficient.

For configuration and installation, size of the resulting backup is probably the determining factor in what gets backed up. You definitely want to back up the site-specific resources and assets. If you don't back up the configured components you will need to start with a fresh install and restore your site-specific resources and assets onto it. You may want to back up the static components/items. However you probably don't want to back up the dynamic/temporary data.

Issues when restoring to a different host

You can't simply take a snapshot of a PAN installation, restore it on a different host, and expect it to run. Notwithstanding specific issues with pan/conf/configuration.html and apache/httpd.conf:

The configured components were modified during the installation so that they knew how to communicate with each other, and this is dependent upon the absolute path within the file system and on the host's IP address.
The license key is dependent upon the host's IP address.

`configuration.html`

Among other things, this file contains information about the hosts in the PAN. This file cannot be transparently restored onto a different PAN. It can be manually edited, but the guidelines for doing so are beyond the scope of this memo.

`httpd.conf`

The Apache configuration file is host-specific. PAN has a tendency to fail in unpredictable ways when run on top of a misconfigured web server. Consider putting your PAN-specific configuration changes into a separate include file if portability of these changes concerns you.