Understanding HADR Archive

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Minimum Zoom version supported: 5.5
 
Archive module can be configured by following this article:  HADR Archive Configuration.

Features

  1. HADR Archive brings the functionality of Archiving assets in a distributed manner.
  2. Multiple OR Single Zoom server can be configured to archive the assets.
  3. Multiple OR Single Zoom server can be configured to run the archive/restore scripts.
  4. HADR Archive can be done on Multiple Zoom servers with shared database.

Archive Process

  1. Archive request received by Zoom server are submitted for execution. Clients will get a notification that archive request is submitted.
  2. Archive request will be aborted, if none of the Zoom servers have valid archive location. Archive location should be given and exist on disk.
  3. Pre-Archive Script will be executed if provided. Archive operation will be aborted if script returns non zero status.
    1. If emails are configured, then failure notifications will be triggered via email.
  4. If assets are eligible for Archiving, they will be marked as Archive. At this level, no data has moved out of database to archive location.
  5. When Zoom database writer server restarts, it will compute the checksum of assets and eventually will mark them as fully archived.
    1. At this stage it is not possible to restore the assets until server is restarted again and transfers the files to Archive Location.
  6. Now when Zoom database writer server restarts again, files will be transferred to Archive location.
    1. Once file transfer finish, Zoom server will run the post archive scripts.
    2. And mail notifications are sent out.

Restore Process

  1. Restore request can only be accepted on archived assets.
  2. HADR restore is done in three phases.
    1. First phase: Run pre-restore scripts if configured.
      1. Note: If script returns exit status zero, then only restore process will move forward, else it would be aborted.
    2. Second phase: Copy/download the archived files to Zoom database location.
      1. Note: This process might be time consuming and depends on number of files and their size.
      2. At least one of the Zoom server must have access to archive location and archive location must contain valid archived files.
    3. Third phase: Marking the files as restored in Zoom database. Only after the successful completion of this this process files would be restored and available to users.
  3. Emails are sent out if case of success or failures.

Example

All Zoom servers with shared database

In this example we assume there are three Zoom servers with shared database. All Zoom servers are configured to use single database location.
Our example servers are:

  1. http://acme-server1:8880 (*database writer)
    1. http://acme-server1:8443
  2. http://acme-server2:8880
    1. http://acme-server2:8443
  3. http://acme-server3:8880
    1. http://acme-server3:8443

All above three servers are configured to use database location: “/acme-network-storage/zoom-database”. This location is present on Network attached storage and shared to each server via NFS.

  • Database location for all three Zoom servers: “/acme-network-storage/zoom-database”.
  • Archive/Restore Scripts are available at: “/acme-network-storage/zoom-scripts/archive”.

Configuring archive module as per above settings

  1. All Zoom servers must be running.
  2. Find out the database writer. See: How to find the database writer.
  3. Log in to the Zoom web management console of the database writer server found in the above steps. Let say in our example: http://acme-server1:8443
  4. Enable Archive in HADR Archive spec. See: How to enable HADR Archive.
  5. Provide archive/restore scripts if required. See HADR Archive/Restore Scripts Configuration.
  6. Configure the mailing list.
  7. Change the peer name for script execution to ACME-SERVER1.
    1. Note: Peer names are Zoom server names given in the HADR spec. Names must be exactly the same across all servers. Peer names are case sensitive.
  8. Save the archive settings.
  9. Now login to acme-server2 and acme-server3 and verify HADR Archive Configuration. They must be exactly the same on all three Zoom servers.
  10. Provide an archive location to the database writer server. See Providing Archive Location.
    1. Note: Archive location is a local setting and will only stay on the server on which it is configured.
  11. Once all settings are saved. The archive module is ready to access archive/restore requests.

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