Virtual TapeServer 8.4 Configuration Guide

Introduction | 3
Note The VTS web interface refers to virtual tapes as “cartridges.” Note that these terms are
synonymous in VTS.
Virtual tape drives respond to mount, write, rewind, read, and unload commands from standard
backup management applications. Virtual tape drives require virtual tape media, and VTS enables
you to create an unlimited number of virtual tapes. A virtual tape is the logical equivalent to a
physical tape. However, unlike physical tape media, virtual tapes can be created in any size because
the data is pooled on low-cost disk storage. A virtual tape contains only the data written to it, with
no wasted space. When a virtual tape is no longer needed, it can be discarded just like a physical
tape. A virtual tape is synonymous with a file in a directory.
Overview of features
The heart of VTS is a middleware tape emulation engine that enables VTS to emulate tape storage to
host servers and provides backup storage for the data on industry standard, low-cost disk arrays.
Data stored in VTS can later be copied to real tape media for archival storage or disaster recovery if
long-term backup copies are required. The advantages of this approach include the following:
l Access to data in VTS is almost immediate, and there is no tape to mount or rewind and no
searching through tape volumes for data files.
l If additional tape storage is needed, you can create virtual tapes using the VTS web interface
without involving the host server. A tape that is individually exported using tape-to-tape
export by VTS is identical to one made by the host application directly and can be read on any
host server, including sites without VTS.
l Dynamic Data Reduction, which allows VTS to compress files as they are written to disk
storage devices. Its use can provide up to 12 times the available storage capacity and reduce
the amount of associated storage costs. This feature uses an “on-the-fly” compression
algorithm that creates little processor overhead and can increase performance and throughput
by decreasing the volume of data written to disk.
l Tape-to-Tape Export, which enables you to export data on a virtual tape to a physical tape in
an external tape drive or library. This provides a one-to-one mapping of virtual to physical
tape. When creating the tape-to-tape export job, you can choose whether the data remains in
virtual tape format or host format. This allows application-aware exports because you have
the ability to name the virtual tapes such that they are the same as a pool of physical tape
cartridges. This then ensures that DR reports created by backup applications are accurate
when a virtual tape has been written to physical tape.
l Dynamic Import provides the ability to dynamically import data from pre-existing physical
tapes in a physical tape device. This enables you to use older tape formats and restore them
to a host. Or, you can convert older physical tapes by importing them and then exporting the
virtual tapes to newer physical tapes. For example, you can import DLT7000 tapes into VTS;
when you import physical tapes, the data on those tapes is stored on virtual tapes. Then, to