Online recovery is performed when Cell Manager is accessible. In this case most of
Data Protector functionalities are available (Cell Manager runs the session, restore
sessions are logged in the IDB, you can monitor the restore progress using GUI, and
so on).
Offline recovery is performed if the Cell Manager is not accessible (for example, due
to network problems, Cell Manager has experienced a disaster, online recovery has
failed, and so on). Only standalone and SCSI Library devices can be used for offline
recovery. Note that recovery of Cell Manager is always offline.
Remote recovery is performed if all Media Agent systems specified in SRD file are
accessible. If any of them fails, disaster recovery process fails over to local mode.
This means that the target system is searched for locally attached devices. If only one
device is found, it is automatically used. Otherwise Data Protector prompts you to
select the device which will be used for restore. Note that offline OBDR is always
local.
Disaster is always serious, however the following factors can exacerbate the situation:
• The system has to be returned to online status as quickly and efficiently as possible.
• Administrators are not familiar with the required steps to perform the disaster
recovery procedure.
• The available personnel to perform the recovery may only have fundamental
system knowledge.
Disaster recovery is a complex task that involves extensive planning and preparation
before execution. You have to have a well-defined, step-by-step process in place to
prepare for, and recover from, disastrous situations.
Disaster recovery process
The disaster recovery process consists of 4 phases:
• Phase 0 (preparation) is the prerequisite for a successful disaster recovery. The
planning and preparation must done before a disaster occurs.
• In Phase 1, DR OS is installed and configured, which usually includes repartitioning
and reformatting of the boot partition, since the boot or system partition of the
system are not always available and the environment needs to be recovered
before normal restore operations can resume.
• The operating system with all the configuration information that defines the
environment with Data Protector (as it was) is restored in Phase 2.
• Only after this step is completed, is the restore of applications and user data
possible (Phase 3).
Disaster recovery guide 25
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