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What is the difference in a destination and a tape in BRU Server?

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Votes: 1
Posted: 09 Jul, 2007
Unlike most other backup applications, BRU Server does not use the concept of a single tape. Instead, backups are written to a destination. A destination may consist of one or more assigned tape slots if you are using a tape library, while a standalone tape drive will only have one destination. Because a standalone drive only offers one destination, the tapes used for a multi-tape archive would still be considered a single destination

Destinations are defined on the “Data Manager” panel of the main interface:

BRU Server Destinations

For library users, there can be multiple destinations defined. In fact, as a minimum we recommend one destination for each physical tape drive in the library. By defining multiple destinations, you will be able to execute simultaneous job operations if you have multiple tape drives in your library – backup, UpStage, or restore – allowing you to reduce wait times for defined jobs.

By Default, a library will have one destination defined when it is initially scanned – “BRAND-default” – where BRAND is the manufacturer of the library such as Exabyte , ADIC, Sony, or others. This destination will consist of no assigned slots and all slots will be placed into the “Free Pool”.

If you only have one tape drive in your library, this default destination may be satisfactory. However, if you have multiple drives available within the library we recommend that you rename this default destination and add an additional destination for each additional tape drive. For example, in an Exabyte 221L with 2 drives, you could create two destinations: EXABYTE-1 and EXABYTE-2. Here we have chosen to keep the brand name as part of the destination name but this is not required. You could have called them ACCOUNTING and ENGINEERING, or 103-99-3ENG and 103-99-3ACC.

It is important to realize that these destinations do not imply that a particular drive within the library will be used and there is no way for you to assign a destination to a specific drive. In a multi-drive library, the BRU Server software will determine which drive should be used based upon the amount of time each drive has currently been in use. This feature is called Autobalancing™ and is designed to lessen the potential of overusing a single drive within your library and thereby increasing the life expectancy of all drives.
Tape Usage and Handling

In addition to BRU Server’s Autobalancing™ of the drive selection being automated, BRU Server also handles tape media differently than most backup applications to provide the longest possible life for your media. With most backup applications, when a backup operation is set to overwrite a series of tapes, the backup will automatically reset the first tape for use to the first slot in the assigned tape pool. This can result in some tapes in a pool being used excessively while others may never be used.

BRU Server’s tape use algorithm is designed to ensure that tapes within a defined destination are used equally. Therefore, overwrite jobs will always start with the least used tape in a destination. For example, if you have a destination with 8 defined slots and the first backup used tapes 1-4, when you next run an overwrite job to that destination, the backup will start on the tape in slot 5 rather than restart with the tape in slot 1.

This means that when handling the media for removal and rotation, you should always remove ALL tapes assigned to a destination, not just the ones that you think were written to in the last backup operation.
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