HP StorageWorks 6000 HP StorageWorks VLS and D2D Solutions Guide (AG306-96028, - Page 26

that allows duplicate data to be detected and stored only once on the HP VLS or D2D system also allows only the unique data to replicate between sites. Because the volume of data being replicated between sites is much less than if the full data set was replicated, you can use lower bandwidth links at correspondingly lower price points. In addition, backup at remote offices can be automated to a local virtual tape library and then replicated back to a regional data center or primary data center allowing end-to-end management from the data center of all data in the remote offices. This transformation is shown in Table 5 which compares the amount of data to transfer both with and without deduplication. The amount of data to back up in this example is 1 TB. Table 5 Estimated Time to Replicate Data for a 1 TB Backup Environment at 2:1 Link Type Data Sent T1 T3 OC12 Link Rate (66% efficient) 1.5 Mb/s Backup Type Without deduplication Incremental 50 GB 4.5 days Full 500 GB 45.4 days Change Rate With deduplication 0.5% 13.1 GB 29 hours 1.0% 16.3 GB 35 hours 2.0% 22.5 GB 49 hours 44.7 Mb/s 3.8 hours 1.6 days 59 minutes 73 minutes 102 minutes 622.1 Mb/s 16 minutes 2.7 hours 4.3 minutes 5.3 minutes 7.3 minutes NOTE: T1/T3 and OC12 are old terms with respect to WAN link terminology. Many link providers use their own names (e.g., IP Clear, Etherflow). This document distinguishes them by their speed using 2 Mbits/sec, 50 Mbits/sec, etc. One consideration with replication is that you must "initialize" the Virtual Tape Libraries with data prior to starting the replication. This ensures that the source and target devices are both synchronized with the relevant reference data to allow them to interpret the changed data (deltas) that comes across the WAN link during replication. Replication Deployment Options You can deploy the HP VLS and D2D systems for replication in many ways depending on your requirements. You should understand the terminology associated with deduplication and replication. The key terminology for replication deployment: • Source: A series of slots/cartridges in a virtual library that act as the source data to replicate. This is the original copy of the backup data, written to and managed by the source site's backup application. • Target or LAN/WAN destination: A series of corresponding slots in another virtual library on another site in another location which receives data from the source library. This is the secondary (disaster recovery) copy of the backup data, managed by the replication system. 26 Concepts