Archive:Media Strategy 3.4

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The SEPuler - an event calendar


Media Strategy

The media used by SEP sesam are administered in media pools using non-ambiguous labels. The labels consist of the pool name and a five-digit number assigned by SEP sesam within the pool. For this reason a pool name may never end with five (5) digits. In the GUI a new media pool is created under GUI->Components->Media Pools->New Media Pool . An important parameter set in the media pool is Locked Days , i.e. how many days a tape from this pool cannot be used, preserving the backup data. This is a number of days and is called End of Life = EOL.

For each media the following information is stored in media archive:

Label              Identification of the media
Media Pool         Name of the pool where the media belongs
ID                 Number within the pool
Write Protection   Can be set up by the user; blocks the media against overwrite until the 
                   write protection is canceled
Backup Day         Date of backup day, SEPsesam uses the date the backup started, e.g. a backup
                   starts at 11 p.m. on January 1, but finishes at 2 a.m. on January 2, a Jan 1 backup  
Locked until       Date from which it can be used again = backup day + Pool_EOL    
Drive Number       of the drive used for backup
Media Type         is compatible only with certain drive types
Loader             in whose magazine the media are currently loaded
Slot               of the magazine
Occupancy          in MB, GB, etc. 
Error Count        accumulated count of potential error messages of the drive for this medium


The fields Write Protection, Loader and Slot can be changed directly by the user.

Write protecting media precludes it being overwritten during backup, preventing data loss. The write protection setting is preserved until the user cancels it manually.

EOL write-protection, however, is automatically controlled by SEP sesam.

Loader and slot numbers must always coincide with the actual location of the media. This is especially valid when using smaller autoloaders that do not have bar code readers. It is physically and technically impossible to recognize manual changes to tapes in the autoloader magazine. If media is removed from the autoloader or entered at random the program will not recognize these changes. It is absolutely necessary to either start an archive adjustment via the GUI or to enter the correct data (loader and slot numbers) directly into the archive.

Media selection is triggered by setting events. The events execute the strategies for media selection, reinitialize the media and prepare the media for the scheduled backups.

Media change using the media event

Entered media should be fully utilized and written on until the end of media (EOM).

For this reason there is no entry for EOM, SEP sesam will request a new medium from the corresponding mediapool automatically when the medium or tape is full.


Every day a new cassette from the mediapool should be used.

When using a single tape drive the media event is not required. By daily inserting a tape without an EOL entry SEP sesam will automatically complete the prior day's backup and (set the data protection) and will initialize the new tape. This method has the advantage that in the event of a holiday, new data will be continually written on the tape in the drive from the end of the last backup (write) until the tape is full.

When using an autoloader a daily media event must be set. Doing so assures that a new medium is used from the loader. The prior days media will be locked using the EOL command set by the administrator.

When using either a single tape or autoloader it is possible to pre-define a medium for a specific purpose. This is useful when certain media are used for month-end, year-end, or for copy purposes.


It is generally recommended to set the media event during regular working hours, for example 10 am, and after SEP NewDay. In this way the request for a new tape, requiring manual change, doesn't occur in the evening or at night when the backup is scheduled to take place.

GET_OLDEST strategy

If there is only one media pool connected to a media event or schedule the GET_OLDEST policy is always applied. This preserves the data on the media for the longest possible time.

If the media event includes a specific label, the system will attempt to find and load it into a drive.

The user must be sure the autoloader magazine is accessible by Sesam or the backup will be blocked.

The GET_OLDEST strategy selects the media

  • with the oldest 'locked until' date in the media pool (= the oldest one)
  • with no set write-protection
  • with already exceeded locked until date

to be used next.

Spare Pools

Blocked backups can be prevented by using SPARE POOLS.

The name of spare pools start with SPARE_. In this situation, initially unused media are inserted and kept for later use. For each type of drive an adequate spare pool should be generated and filled with the compatible media.

These spare pools are used by media events in case media from the actual pool are inaccessible. A medium is moved from the compatible spare pool to the pool currently being accessed by the backup. Here the spare media migrate from spare pools to the working pools resulting in a dynamic increase of media pool size depending on the amount of data being backed up.

SPARE pools can be used for automatic insertion of new media into working media pools. For big loaders the media are pre-initialized with labels of SPARE pools at SEP AG saving time during the installation phase. The media then migrate as needed to the working pools on the production system.

Media utilization can be influenced in following ways:

  • locking time-limits of media pools
  • set/unset write-protection in media archive
  • media events in SEPuler
  • modify the locking date of a media in archive to an already exceeded date and execute a media event

Archive Adjustment

An Archive Adjustment makes a comparison between media in the loader carousel or magazine and the Sesam media archive database. An archive adjustment is mandatory whenever the contents of a loader carousel has been altered. This is especially true after inserting new media or used media which has not yet been registered (initialized) by SEP sesam.

Once new media has been inserted in the autoloader it is necessary to execute an archive adjustment. The option Automatic new Entry is selected to automatically enter the new media.

The adjustment is started using the GUI->Components->Loader->Content->Archive Adjustment.

When selecting Archive Adjustment be certain that the autoloader being realigned is selected in the GUI Window, i.e. make sure the target device is at the top of the adjustment task. When using the command line the task must include the name of the target autoloader or tape device.