Introduction
CP 3100 Theory of Operation
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lates the robot’s actions using firmware, and organizes the capacity of the disk drive into a set of vir-
tual tape cartridges (VTCs).
The number of data cartridges in a physical autoloader is limited by the mechanical constraints of
the autoloader’s magazine. A virtual autoloader does not have the same constraint and therefore
can contain many more virtual tape cartridges. Since the virtual autoloader appears to the host —
and behaves — as a physical autoloader, virtual tape cartridges appear to the host and behave just
like physical tape cartridges. The CP 3100 manages the relationship between the virtual tape car-
tridges visible to the host backup software and the physical tape cartridges visible only to the CP
3100, ensuring data can be restored from either disk or tape.
The Flow of Data
The Backup Process
During a backup, the host backup software moves data from the host to the CP 3100's virtual auto-
loader, writing data to the disk drive in the same format it would to a physical autoloader. Once the
backup to the virtual autoloader is complete, the CP 3100 copies the data to the attached physical
tape drive — in the background and without intervention from the host or user — creating an exact
replica archive on tape.
Figure 1.
Backup Data Flow from a Host to a CP 3100 Virtual Tape Cartridge
The Restore Process
During a restore, the host backup software directs the CP 3100's virtual autoloader to insert the tape
containing the file(s) to be restored. The virtual autoloader checks its virtual tape cartridges to see
whether the virtual tape matching the backup software's request is available. If it is, the virtual auto-
loader “inserts” the appropriate virtual tape cartridge and restores the file(s), at disk speed, to the
host. Since this occurs with a virtual autoloader, and virtual cartridges are always available, tape
insertion is instantaneous and the restoration process begins immediately.
1. Host backup software
sends data to CP3100.
2. Background archive from
CP3100 to physical tape.
