Setting up Redundancy

Redundancy can be obtained in many ways. Here are the more common configurations.

  • Manual failover to warm standby using an IP address w/ manual failback
  • Manual failover to warm standby using a host record w/ manual failback
  • Automatic failover to warm standby w/ automatic failback

Method #1: Manual failover to warm standby using an IP address w/ manual failback

With a failover to warm standby configuration you use two servers with Printer Installer installed on both and a DNS record (prrinters.domain.com) pointing to an IP address that is added to the primary Printer Installer server.  The primary server has a read/write database and the secondary server has a read-only database. The secondary server's Printer Installer database is updated regularly (warm standby) from the primary's database. Upon failure of the primary, the IP address is added to the secondary server, which accepts all read requests until the primary server can be brought back online, allowing users to browse the portal and manually install printers and allows the client to check-in and install printers while the primary server is down. Changes in Printer Installer Administrator are denied and end user write requests (such and print job audit records) are quietly ignored and stored on the user's workstation until the client contacts a primary Printer Installer server.

Setup

To setup Printer Installer for manual failover to warm standy redundancy, do the following:

  1. Install and configure Printer Installer on the server that will be the primary Printer Installer server.
  2. Add an additional IP address to the server. This additional IP address will be called the "PI application IP address".
  3. Create a DNS host record (example: print.domain.com) pointing to the Printer Installer application IP address.
  4. Setup Printer Installer Clients to use the host record for the HOMEURL command-line option. Also, have any links that will open the Printer Installer Portal refer to the host record.
  5. Install Printer Installer on secondary Printer Installer server.
  6. Configure the secondary server's Printer Installer database to be read-only.
  7. Automate the Printer Installer database export from the primary Printer Installer server and import to the backup Printer Installer server.
  8. Setup your regular file backup (shadow copy) to copy the exported database file daily so that if a corrupt primary database gets exported and imported to the secondary server you can still restore/import a good database from backup.

Automating the Printer Installer database export from the primary Printer Installer server and import to the backup Printer Installer server:

  1. Setup is complete. See "Failover to Secondary" below for instructions on failing the Printer Installer application to the secondary server.


Failover to Secondary

To perform the manual failover to the secondary warm standby Printer Installer server, do the following:

  1. Disable importing the primary server’s database to the secondary server.
  2. Remove the Printer Installer application IP address from the primary server.
  3. Add the Printer Installer application IP address on the secondary server. The secondary server will now service all Printer Installer requests.  
    Note:  Because the database is marked as read only, only read requests will be processed, all write requests will be denied.  This is desired so that print job records and other changes are not allowed to be inserted into the database. When the primary server is brought back online then the print job records, that have been denied, will be inserted into the primary database.


Failback to Primary

To failback to the primary server, do the following:

  1. Remove the Printer Installer resource IP address from the secondary server.
  2. Add the Printer Installer IP address to the primary server.
  3. Re-enable importing the primary server’s database to the secondary server.

    Note: Be sure to never have the Printer Installer IP address active on more than one server.

Method #2: Manual failover to warm standby using a DNS record w/ manual failback

With a failover to warm standby configuration you use two servers with Printer Installer installed on both and a DNS record (prrinters.domain.com) pointing to the primary Printer Installer server.  The primary server has a read/write database and the secondary server has a read-only database. The secondary server's Printer Installer database is updated regularly (warm standby) from the primary's database. Upon failure of the primary, the DNS record is changed to point to the secondary server. The secondary server then accepts all read requests until the primary server can be brought back online, allowing users to browse the portal and manually install printers and allows the client to check-in and install printers while the primary server is down. Changes in Printer Installer Administrator are denied and end user write requests (such and print job audit records) are quietly ignored and stored on the user's workstation until the client contacts a primary Printer Installer server.

Note: Because "Manual failover to warm standby using an IP address w/ manual failback" allows end users to be able to connect to the backup server instantly, it is recommended over this method. This method requires you to set a low TTL (time to live) value on the DNS record, causing the workstations to check in with the DNS server at each TTL interval, causing increased network traffic. Additionally, with this method the Printer Installer service will not be available until the workstation checks in with the DNS server and gets the new Printer Installer DNS record's IP address. The "Manual failover to warm standby using an IP address w/ manual failback" allows for instant access to the backup server and no needless DNS check-ins.

Setup

To setup Printer Installer for manual failover to warm standy redundancy, do the following:

  1. Install and configure Printer Installer on the server that will be the primary Printer Installer server.
  2. Create a DNS host record (example: print.domain.com) pointing to the primary server. Set the TTL value on the record to a short amount of time so that end user's computers will quickly notice when you change the record to the secondary server's IP address.
  3. Setup Printer Installer Clients to use the host record (example: printers.domain.com) for the HOMEURL command-line option. Also, have any links that will open the Printer Installer Portal refer to the host record.
  4. Install Printer Installer on secondary Printer Installer server.
  5. Configure the secondary server's Printer Installer database to be read-only.
  6. Automate the Printer Installer database export from the primary Printer Installer server and import to the backup Printer Installer server.
  7. Setup your regular file backup (shadow copy) to copy the exported database file daily so that if a corrupt primary database gets exported and imported to the secondary server you can still restore/import a good database from backup.

Failover to Secondary

To perform the manual failover to the secondary warm standby Printer Installer server, do the following:

  1. Disable importing the primary server’s database to the secondary server.
  2. Change the DNS record to point to the secondary server.  When end user's workstations update with the new IP address of the DNS record, the Printer Installer requests will be sent to the secondary Printer Installer server.

Failback to Primary

To failback to the primary server, do the following:

  1. Change the DNS record to point to the primary server.  When end user's workstations update with the new IP address of the DNS record, the Printer Installer requests will be sent to the primary Printer Installer server.
  2. Re-enable importing the primary server’s database to the secondary server.

Method #3: Automatic Failover to Warm Standby

With automatic failover to warm standby you install Printer Installer on two servers, one install on the primary Printer Installer server and another install on the secondary server. Then configure a service like NLBS or similar to direct requests that are made to the Printer Installer application url to go to the primary server until the primary server fails. Upon failure it directs requests to the standby secondary server. When the primary server is back online it directs the requests to the primary server again.

Note:
When the secondary server is accessed by user's clients, only read requests are serviced. Administrator changes, WPSL updates and print job audit records are not recorded (they are stored on the local workstation until they can be recorded by the primary server).

To configure automatic failover to warm standby do the following:

  1. Install and configure Printer Installer on the server that will be the primary Printer Installer server.
  2. Install Printer Installer on the server that will be the secondary Printer Installer server.
  3. Mark the secondary Printer Installer server as a read-only server.
  4. Automate the Printer Installer database export from the primary Printer Installer server and import to the backup Printer Installer server.
  5. Create a DNS host record (example: print.domain.com) that will be used to access the Printer Installer application and direct it to the NLBS service.
  6. Configure NLBS to direct requests made to the Printer Installer URL to always go to the primary Printer Installer server unless the primary Printer Installer server is offline, then have the requests go to the secondary server until the primary server is brought back online.
  7. Setup your regular file backup (shadow copy) to copy the exported database file daily so that if a corrupt primary database gets exported and imported to the secondary server you can still restore/import a good database from backup.