PSQL Vx Server Product Guide (v11)

Data Backup

The chapter ログ、バックアップおよび復元 in Advanced Operations Guide discusses the data backup solutions provided with Pervasive PSQL. In addition to those solutions, Pervasive PSQL Vx Server includes the following:

If your backup software is not aware of the Microsoft Volume Shadow Copy Service (VSS), you can use Pervasive Backup Agent with your backup software. The VSS framework is included with Windows Server 2003 and newer operating systems.

If your backup software is VSS aware, Pervasive PSQL VSS Writer is automatically invoked during VSS backups. You do not need to use Pervasive Backup Agent if you backup software is already VSS aware.

Pervasive PSQL VSS Writer and Pervasive Backup Agent can be used together, but there is no advantage in doing so. Your backup process will be more streamlined if you select one method or the other.

Pervasive Backup Agent

Pervasive Backup Agent is an optional product included with Pervasive PSQL Vx Server. By default, it is not installed. If you want to install Backup Agent, you must install it from the Pervasive PSQL Vx Server media after you install Pervasive PSQL Vx Server. Select Pervasive Backup Agent on the installation selection dialog. No separate license for Pervasive Backup Agent is required if it is installed on the same machine as Pervasive PSQL Vx Server.

Pervasive Backup Agent provides a quick and simple method for you to set and manage continuous operations on your Pervasive PSQL database files. Setting and managing continuous operations is a critical piece when backing up your Pervasive PSQL databases without using Microsoft Volume Shadow Copy Service (VSS). Backup Agent automatically handles setting and managing continuous operations on your open files so that your data is still available from your application during your backup. Once the backup procedure is complete, stopping Backup Agent automatically takes the files out of continuous operations and rolls in all the changes captured during the backup.

Pervasive Backup Agent is compatible with many popular backup applications on the market. Note that the backup application must be able to issue commands to start and stop other applications (so that the commands can start and stop Pervasive Backup Agent).

For details on Pervasive Backup Agent, see Pervasive Backup Agent Guide.

Pervasive PSQL VSS Writer

The Microsoft Volume Shadow Copy Service (VSS) consists of Writer, Provider, and Requestor components. Pervasive PSQL Vx Server supports VSS with only a Writer component, Pervasive PSQL VSS Writer. Pervasive PSQL VSS Writer is a feature of the database engine and is available for use after Pervasive PSQL Vx Server is installed. Pervasive PSQL VSS Writer is available only on Windows operating systems.

(For more information on Volume Shadow Copy Service, refer to the Microsoft Web site document, A Guide for SQL Server Backup Application Vendors.)

Overview

During VSS snapshots, Pervasive PSQL VSS Writer quiesces all disk I/O write activity to all Pervasive PSQL data and transaction log files, regardless of the volume on which they reside. After the snapshot is taken, Pervasive PSQL VSS Writer allows all disk I/O to resume; this includes any writes that were deferred during the quiesced period.

Pervasive PSQL VSS Writer never quiesces disk I/O read activity allowing normal database processing to continue during the quiesced period as long as writes are not required. Pervasive PSQL VSS Writer operates normally during the backup phase, although performance will likely be reduced due to the backup activity of the VSS service and VSS Requestor.

The Microsoft Volume Shadow Copy facility allows Backup and Restore products to create a shadow copy for backup in which the files are either in one of the following states:

  1. Well-defined and consistent state
  2. A crash-consistent state (possibly not suitable for a clean restore)

Files in the VSS snapshot will be in the well-defined and consistent state if all of the following are true:

  1. The file’s writer is VSS-aware
  2. The Backup and Restore product recognizes and notifies the VSS-aware writer to prepare for a snapshot
  3. The VSS-aware writer successfully prepares for the snapshot

Otherwise the writer’s files are backed up in the crash-consistent state.

VSS Writer Details

The following items discuss specifics about Pervasive PSQL VSS Writer.


Licensing

Hypervisor Products Compatibility