HP 12000 HP VLS Solutions Guide Design Guidelines for Virtual Library Systems - Page 13

Figure 3 Basic Write-to-disk Setup Table 1 VLS Compared to Application-based Write-to-disk Setup and management complexity Data compression Performance Cost Virtual tape devices Sets up just like a physical tape library. Write-to-disk Requires configuration of RAID groups, LUNs, volumes, and file systems. Software or hardware enabled (software compression generally decreases performance). No device-side data compression available. Hardware devices are tuned for sequential read and write operations. Performance dependent on target array or server. More expensive acquisition cost. Free or licensed per TB in most backup Backup software licenses as if physical library applications. or per TB. Higher management overhead. Storage efficiency gained through compression. Lower management overhead. Business Copy Using a business-copy solution (array snapshots/clones) generally involves a much higher cost than a virtual library system. You might, however, implement such a solution if: • Virtually instant recovery is critical. • You need to leverage a high-availability investment. • You are doing image recovery rather than file recovery. • You need a zero downtime solution. Disk-based Backup and Virtual Tape Libraries 13