Cp 3100 Theory Of Operation - Certance CP3100 D2D2T User Manual

Introduction
Migrate
Physical Tape Cartridge (PTC)
Physical Tape Drive (PTD)
RemoteAdmin
Storage Pools
Inventory/Virtual Device
Inventory
Virtual Loader Device (VLD)
Virtual Tape Cartridge (VTC)
Virtual Tape Drive (VTD)

CP 3100 Theory of Operation

The following sections describe the theory of operation behind the CP 3100. For more information
about CP 3100 operation, see Appendix A.
Overview
The CP 3100 emulates a DAT autoloader, with a single DDS-4 or DAT 72 tape drive on the host
SCSI bus. To perform a backup operation, the backup software executing on the Host Initiator treats
the CP 3100 as a DDS-4 or DAT 72 autoloader and tape drive.
A physical tape autoloader automates the backup/restore process by receiving commands from the
host software to the mechanical device in the autoloader to insert tapes into and remove tapes from
the tape drive. By emulating a tape autoloader, you can use the same host software and use the disk
drive as a "virtual autoloader" that appears to the host and behaves exactly like a real autoloader.
Instead of a robot that grabs physical tapes, the virtual autoloader in the Certance CP 3100 emu-
The process by which the CP 3100 removes data from the Storage Pool
to make room for newly backed up data. Data will only be migrated if it
has been successfully archived (written to physical tape) previously.
Data is migrated using a least recently used (LRU) algorithm, which
migrates data starting with the oldest backed-up data.
An actual tape cartridge used for archive and restore operations.
The DAT tape drive attached to the CP 3100 Archive SCSI bus.
The tool the Administrator uses to access the CP 3100's configuration,
management, and control interface via a Web browser-enabled Ether-
net connection.
Storage Pools are created on the CP 3100's hard disk(s) and are used
by the Virtual Loader to read/write Virtual Tape Cartridge data and
control information. Storage Pools are the method by which host data is
organized into Virtual Tape Cartridges.
The first time that the CP 3100 discovers a new PTD on the Archive
SCSI Bus, it creates and initializes a Virtual Tape Drive (VTD) and a Vir-
tual Loader Device (VLD) populated with Virtual Tape Cartridges (VTCs).
These VTD, Virtual Loader Device (VLD), and VTCs are accessed and
managed through a Virtual Device Inventory (VDI).
Part of the Embedded Server that emulates a Certance DAT autoloader
with a configurable number of virtual slots. The default number of virtual
slots is 25.
When initialized, the CP 3100 creates virtual tape cartridges in all VLD
slots. These virtual tape cartridges are initially empty. Once written (and
until erased or overwritten), a VTC logically contains all data written to
it. Data blocks will be available either in a Storage Pool or on a PTC
associated to the particular VTC. Upon a restore operation, the
CP 3100 determines the location of a requested data block and
retrieves the data from either the VTC or requested PTC.
The Virtual Tape Drive is part of the CP 3100 firmware that emulates a
DDS-4 or DAT 72 physical tape drive.
CP 3100 Theory of Operation
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