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Scale-out Backup Repositories

Data Locality or Performance Mode?

  • When using REFS / XFS or integrated deduplication devices the mode has to be configured to Data Locality to make use of efficient synthetic operations.
  • To leverage the Performance Mode you need at least two extents
  • Performance mode increases the failure domain - a backup chain is split over two extents per default. Thus the loss of one of the two corrupts the entire chain. This trade-off between increased failure domain and increased performance has to be evaluated case by case.

Block Size

The created data-block-objects in the object storage are based on the backup’s configured block size (Storage optimizations). The default is Local Target and refers to an uncompressed block size of 1024 KB. Every block is offloaded as a single object in the object storage and thus requires one API call per read or write operation (GET/PUT).

For the same amount of data a larger block size would mean less objects and less API calls. On the other hand larger block sizes creates significantly larger incremental backups. It also means a higher probability of changes in the block which reduces the efficiency block cloning.

Experience shows that the default Local Target setting with the uncompressed 1024 KB block size is the best general purpose setting and should be configured in most cases.


References


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