HP 9000 Virtual Library System - Manual (Page 50)

•
The destination library can only be used for copy operations.
•
Echo copy is a full tape copy, rather than an incremental change copy, so it can be an
inefficient use of media if you are using non-appending copy pools in your backup jobs.
An echo copy pool is used to define which destination library slots are to be echoed into a specified
virtual library. Automigration then monitors the echo copy pool slots to detect cartridge loads/ejects
in the destination library, and automatically synchronizes the virtual cartridges to the destination
cartridges, creating the matching virtual cartridges as needed.
This means that when new destination tapes are loaded, automigration will automatically scan
them (read the backup application headers) and then automatically create matching virtual cartridges
in the virtual library specified for that echo copy pool.
NOTE: The automatic scanning of new cartridges can take a long time if all the tape drives in
the destination library are busy with higher priority operations such as copies. Therefore, it is best
to load new tapes when copies are not running.
Data written to echoed virtual cartridges will be automatically copied onto matching destination
tapes based on the echo copy policy. An echo copy policy defines for each source virtual library
the copy window (start and end times), the copy on eject option, and the time in days for expiration
after eject. If destination tapes are ejected, the matching virtual tapes are automatically moved to
the firesafe and are deleted at the policy-defined expiration time. This ensures the device does not
fill up its disk space with older cartridges. See
Creating an Echo Copy Pool (page 55) to create
a policy. If virtual tapes are ejected by a backup application, the matching destination tapes are
also automatically ejected into the destination library mailslot when the copy operation is complete.
When an echo copy is ejected (mailslot eject box is checked), the echo copy is performed, then
the eject is carried out. This results in the echo copy being placed in the device's firesafe and
maintained according to the established policy. If a destination tape was ejected while a copy
was pending, then notifications in the VLS GUI will inform the user that they have interrupted the
copy process.
Replication Concepts
Replication provides automigration via LAN/WAN between two VLS devices. Because replication
is a feature of automigration and uses the same Echo Copy policies that allow flexible cartridge/slot
based configuration, any number of different replication configurations can be supported. You
establish a replication policy and echo copy pools using Command View VLS in the same way
you set up automigration with a destination library on the SAN.
During replication, the source VLS copies data to the echo copy pools on a replication library that
is on the source. During the user-defined availability window, this replication library migrates data
to the destination library, known as the LAN/WAN replication target.
The following are two of many possible replication configurations:
•
Data center to data center
Designate one VLS as the source and a second VLS as the destination. Configure the destination
VLS to present a LAN/WAN replication target that is visible to the source VLS. The source
VLS performs normal backups during the regular backup window, and during the availability
window the source virtual cartridges automatically migrate to matching virtual cartridges on
the destination VLS. The same configuration is also used in the other direction so there is a
backup library and a LAN/WAN replication target library on both devices.
•
Branch office to a main data center
Divide a single destination target into multiple slot ranges to allow a many-to-one configuration
without needing a separate replication library for each branch office. In this way, the VLS
replication can scale to hundreds of branch offices all replicating to a single large device.
50 Automigration/Replication