HP D2D D2D Best Practices for VTL, NAS and Replication implementations (EH985- - Page 100

The final total source and target configuration is shown below. Example NAS and VTL configurations Map out the interaction of backup, housekeeping and replication for sources and target With HP D2D Backup Systems it is important to understand that the device cannot do everything at once, it is best to think of ―windows‖ of activity. Ideally, at any one time, the device should be either receiving backups, replicating or housekeeping. However this is only possible with some careful tuning and analysis. Housekeeping (or space reclamation, as it is sometimes known) is the process whereby the D2D updates its records of how often the various hash codes that have been computed are being used. When hash codes are no longer being used they are deleted and the space they were using is reclaimed. As we get into a regular ―overwriting pattern‖ of backups, every time a backup finishes, housekeeping is triggered to happen and the deduplication stores are scanned to see what space can be reclaimed. This is an I/O intensive operation. Some care is needed to avoid housekeeping causing backups or replication to slow down as can be seen below. 100