7 Backup, restore, and recovery
This chapter includes the following topics:
•Defining your backup strategy, page 219
Introduction
There are several methods that you can use to increase safety of data in the FSE implementation. Nevertheless, if data loss occurs, FSE includes features which help recreating data that has been lost in disaster on any component of the FSE implementation. These features are FSE backup, FSE restore and FSE recovery. FSE restore can only be used if FSE backup has been performed before and backup images are available, while FSE recovery does not depend on any other processes.
When user data on HSM file systems is concerned, an appropriate level of their safety can be achieved by properly configuring migration policies for the belonging FSE partitions (see section ”Migration” on page 127), considering multiple copying (see section ”Multiple copying” on page 147), and executing periodic monitoring of physical condition of FSE media in the assigned FSE media pools (see section ”Checking the status of media” on page 117). If disaster occurs on an HSM file system, you can use the recovery feature of FSE to completely recreate damaged or destroyed HSM file system. FSE recovery recreates data and metadata on HSM file system from the belonging Name Space Catalog, which is part of File System Catalog.
Besides user data, FSE implementation also includes other data which are essential for normal operation of FSE. These data are referred to as FSE databases and system files, and contain global configuration files, configuration of FSE resources, not yet migrated metadata, and other entities. They are located on the consolidated FSE system or FSE server, depending on the type of your FSE implementation. To maintain appropriate level of safety of these data, you can equip the FSE server host with a RAID storage subsystem (see the latest support matrices), organize and prepare local file systems (see the FSE installation guide for a particular platform, chapter ”Preparing file systems for FSE”), and define a thoughtful FSE backup policy (see section ”Defining your backup strategy” on page 219). In case of disaster on the FSE server host and when the FSE databases and system files are affected, you can use the FSE restore feature to restore a complete FSE server state from an FSE backup image. As an alternative, when File System Catalogs are only affected, FSE recovery can be used to completely recreate each particular File System Catalog. In this case, the FSE recovery process uses Fast Recovery Information and metadata from FSE media to build a File System Catalog from scratch.
NOTE: Backup and restore of FSE clients is not supported. During backup, only the
If all hosts of the FSE implementation are struck, FSE restore and FSE recovery processes must be used in sequence to revert the FSE implementation into operable state: the FSE server needs to be restored, and HSM file systems on the FSE clients need to be recreated using the HSM file system recovery functionality.
The next sections provide helpful hints on how to define your backup strategy, recommendations on recreating your data, and information on how to recover from an actual data loss.
Defining your backup strategyTypically, if you only perform FSE backup on a regular basis and according to recommendations, you are only able to restore FSE databases and system files on the FSE server. You should also consider using FSE recovery as a method of recreating your data, and define your backup strategy accordingly.
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