By creating a backup event, you select the backup level, set event priority and specify where to back up your data to. You can create an event for a specific task or for a task group. The latter enables you to trigger all the tasks in the task group with a single event.
When configuring a backup event, you also select the backup level you want to perform.
SEP sesam provides four different backup levels: full, differential, incremental and copy. The backup level is specified when creating a backup event in the Main Selection -> Scheduling -> Schedules -> New Backup Event.
The following backup levels are available:
A FULL backup always copies all data specified by the backup task, regardless of whether it has been changed or not. A saveset created as FULL is the basic saveset for subsequent DIFF or INCR savesets. While the backup time of a full backup can be significant, restore is fast and simple since only one backup saveset is required. Information about the backup status is stored in the SEP sesam database. Note that the archive bits are not deleted on Windows systems. If you want to force-reset of the archive bits, you can enter the command -o clear_archive in the backup options.
A DIFF (differential) backup saves only data which was created or changed after the last FULL saveset had been created (of the same task). A differential backup is faster than a full backup, however, to restore the whole data source, first the saveset of the full backup has to be restored followed by restore of the DIFF saveset. For this, SEP sesam provides generation restore that enables browsing for and selecting for restore all generations of backed up files since the last full backup.
An INCR (incremental) backup saves only data which was created or changed after the last backup (FULL, DIFF or INCR) of the same task. This is the fastest backup method and requires the least storage space. Restoring from incremental backups is the slowest, because it requires all related savesets to be copied back – the saveset of the last full backup as well as all INC backups. You should consider the advantages of time and resources when planning your backup strategy. A combination of FULL backups stored to tape drives, and DIFF or INC backups stored to virtual disk media is a common method.
A COPY backup is a full backup that has no influence on following differential (DIFF) or incremental (INCR) backups. For the treatment of archive bits, see FULL backup above. COPY backup is usually used for additional full backups, e.g., monthly backups, or backups for archiving, i.e. removal from storage.
|In case no initial FULL backup exists, differential (DIFF) or incremental (INCR) backups are automatically performed as FULL backups.
Failover backup event
To minimize failed backups due to unavailable media pool, you can specify a failover backup event when configuring the backup event. In case the configured media pool is not available for writing for some reason (out of space, no free media, RDS cannot be reached) and the backup event cannot be successfully performed, the failover backup event is performed instead. If the failover backup event is activated the data storage settings of the original backup event are replaced with the settings from the failover backup event (media pool, drive, interface, follow up, migration task). The task, backup level and other options (for example, Enforce FULL) of the original backup event are preserved.
- From Main Selection -> Scheduling -> Schedules, right-click the schedule for which you want to create a new event and then click New Backup Event.
- Under the Sequence control, set up the Priority of your backup event. SEPuler always executes the schedules with the highest priority first. The default priority level is 1, which is the lowest priority (the highest priority is 99). The only exception are schedules with priority 0, which override all other priorities and are always executed.
For details, see Setting Event Priorities.
You can also enable Blocking date. This option should be used together with high priority for special events. If checked, events of the same type but of a lower priority will be blocked, ensuring that the backup will be processed even if other backups are scheduled for the same time.
- Under the Object, select the task or a task group to which you want to link this event.
- Under the Parameter, select the Backup level.
- For DIFF and INC backups you can use the Enforce FULL and Enforce FULL when last FULL has failed options.
Enforce FULL option ensures that a FULL backup is run within the specified interval. For example, setting the number to 7 will enforce a full backup every seven days instead of an incremental or differential backup. This ensures that a full backup is always performed within the specified time interval.
With Enforce FULL when last FULL has failed option, the system checks whether the last FULL backup was successful or run with warning each time before backup is performed. If the last FULL backup was terminated or run with error, the INC/DIFF backup to be started is automatically executed as FULL backup.
However, once you have decided on your backup schedule, you should consider the advantages and disadvantages of enforced full backup frequency, as it is slower than other backup levels and has the highest storage space requirements. For more information, see Enforcing Full Backup.
- From the Hot/Cold backup drop-down list, select the execution parameter (hot or cold backup).
- From the Media pool drop-down list, select the target media pool to which the data will be backed up. If you want to enable source-side deduplication, you have to select a media pool that is combined with an Si3 deduplication store backend.
- Optionally, specify the drive number of the drive that will be used to write the data. Typically, you use this if you have configured additional drives and you want to assign a dedicated drive exclusively for backup. For details, see option Create second drive in Configuring a Data Store.
- Optionally, from the Interface drop-down list, if you do not want to use the default client interface, you can select another configured TCP/IP-name of the client. You can use this option to direct the data flow over a particular network connection to enable smooth execution of backups without blocking other network activities.
- Optionally, enable SEP Si3 source-side deduplication. This check box is only available if you have a configured Si3 deduplication store and you have previously selected the Si3-related media pool.
- In the Options field you can configure additional backup options to be performed with this event. For more information see Specifying additional backup options.
- In the Migration task drop-down list you can set a follow-up migration task.
- In the Follow up field you can configure events that are triggered on the SEP sesam Server once the initial event has completed. You can set up a migration, a saveset verify and other actions to be triggered immediately after a backup or other event is completed. For details, see Follow-up events.
- In the Failover backup event drop-down list you can select a failover backup task event. This event will be started if the original task event cannot be executed successfully because data storage (media pool or data store) is not accessible.
If the failover backup task event is activated, the data storage settings of the original backup event are replaced with the settings from the failover backup event:
- media pool
- follow up
- migration task
|Make sure your INC chains do not get too long. You can use the Enforce FULL option for this (see below).
Note, however, that it is difficult to give a practical recommendation for the recommended length of the INC chain, as it depends heavily on the performance of the system and also on the size of the FULL and INC backups. As a rule, FULL is recommended once a week and at least once a month. Since long backup chains are inefficient and more vulnerable if something goes wrong because the backups in the chain depend on each other, and because they can simply become too long to restore (no more storage available, takes too long), SEP AG strongly recommends setting up regular FULL backups to avoid such problems, and setting the limit to up to 100 incremental backups. For an example of how to implement a backup scheme, see GFS Backup Retention Strategy.
You can view the status of your backup jobs in the GUI (Monitoring -> Last Backup State or Job State -> Backups) or SEP sesam Web UI. The backup status overview provides detailed information about the last run of backup jobs, including the task name, start and stop time of the last backup, backup level, data size, throughput, assigned media pool, etc.