HP 12000 HP VLS Solutions Guide Design Guidelines for Virtual Library Systems - Page 11
Typical VLS Environments, HP Virtual Tape Library Product Range - ups
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Figure 2 HP Virtual Tape Library Product Range Typical VLS Environments In a typical enterprise backup environment, there are multiple application servers backing up data to a shared tape library on the SAN. Each application server contains a remote backup agent that sends the data from the application server over the SAN fabric to a tape drive in the tape library. However, because backup over the SAN is single-threaded (a single host is backing up to a single tape drive), the speed of any single backup can be limited. This is particularly true when the environment has high-speed tape drives such as Ultrium 2 or Ultrium 3. The hosts simply cannot keep the drives streaming at capacity. NOTE: HP Ultrium drives will adjust the tape speed to match the data stream to prevent "back-hitching." However, the tape drive is still not operating at optimal performance and cannot share bandwidth with another backup job. Enterprise data centers with slow SAN hosts in the environment may be unable to utilize the full performance of high-speed tape drives. Also, shared tape libraries on the SAN can be difficult to configure both in the hardware and in the data protection software. Typical D2D Environments In a typical entry-level or mid-range backup environment, the backup application is performing LAN backups to a dedicated (non-shared) backup target such as a tape library connected to the single backup server. Multiple instances of the backup application will generally each require their own dedicated backup target. These environments may also be remote branch offices, each with their own local backup application. As with the VLS, the backup speed of a single host backing up to a single tape drive is normally limited by the host (which cannot stream high-speed tape drives such as LTO), so currently tape backups use multiplexing to interleave multiple hosts' backups together into a single tape drive impacting restore performance. The addition of a D2D device to these environments allows de-multiplexing of the backups so that restore performance is improved, the deduplication allows Disk-based Backup and Virtual Tape Libraries 11