HP StorageWorks 6000 HP StorageWorks VLS and D2D Solutions Guide (AG306-96028, - Page 148

nodes in the VLS. If the copy window does not need maximum copy performance, you can use even fewer tape drives per node. For example, a 4-node VLS9000 device that needs to automigrate 64 TB every night within an eight hour copy window (that runs after the backups are complete) requires an aggregate copy performance of 2200 MB/sec. With a 100-120 MB/sec per copy stream, this implies a tape library would need 18-22 LTO3/LTO4 tape drives to achieve this copy performance. Remember these tape drives should be evenly spread across both back-end Fibre Channel ports of every VLS node. In other words, half the drives should be connected to the first back-end Fibre Channel port on every node, and the other half should be presented to the second back-end Fibre Channel port on every node. Restoring from Automigration Media When using automigration to create physical backups, if the destination tape is still loaded in the destination library, its matching virtual cartridge will still be present in the virtual library. In this case, the user can simply restore from the virtual cartridge using the backup application. If the destination tape has been ejected from the destination library, the user has the following options: 1. If the automigration virtual cartridge still exists in the firesafe (for example, if the policy-defined retention period has not expired), use Command View VLS to manually move the cartridge back into the virtual library. You can then restore from the virtual cartridge using the backup application, and then move the cartridge back to the firesafe. 2. If the automigration virtual cartridge has been deleted from the firesafe, retrieve the physical cartridge by one of the following methods: • Load the physical cartridge into any compatible physical drive or library that is visible to the backup application and restore from that tape using the backup application. • Load the physical cartridge into the destination library and use Command View VLS to perform a Load Media for Restore, which copies the entire destination tape back into a virtual cartridge. You can then restore from the virtual cartridge using the backup application. NOTE: Customers may choose to configure their devices such that there are additional, unmapped slots in the virtual library. These additional virtual slots can be used for backups so that even if the physical slots are all full, there are still spare slots available to hold the cartridges needed for restore. Another option is to have a separate virtual library for restore operations. VLS Accelerated Deduplication HP Accelerated deduplication technology is designed for optimal performance and scalability to meet the needs of enterprise data centers. It offers the following features and benefits: • Leverages object-level differencing code, which targets matching backup "objects." Rather than comparing the current backup with every byte of data stored on the device, Accelerated deduplication can compare backup objects from the current backup to matching objects from the previous backup, where there is likely to be duplicate data. This allows the deduplication to be performed faster, consuming fewer resources. • Is performed as a post-process. This delivers the fastest possible backup performance, because there is no loss of bandwidth to the normal backup window. • Allows data to be retained longer because redundant information is removed from previous backups, freeing disk space. 148 Virtual Library Systems