HP StorageWorks 6000 HP StorageWorks VLS and D2D Solutions Guide (AG306-96028, - Page 141

Echo Copy Concepts, Implementation, Echo Copy Pools

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Echo Copy Concepts Echo copy essentially acts as a transparent disk cache to the physical library, so that echo copy jobs can be performed at times other than the peak backup window. Once automigration is set up, echo copy operations are automatic and seamless to the user. During the normal backup window, the backup application writes to virtual cartridges. Each virtual cartridge that pertains to an echo copy pool has header information that matches a physical cartridge in the tape library. During the user-established automigration window, data migrates from each virtual cartridges to its matching physical cartridge. Echo copy is managed through the automigration software, not the backup application. For that reason: • The destination library is not visible to the backup application, so it does not need licensing. • Copy traffic is no longer routed through the SAN. • Maximizes performance of high-speed tape drives by freeing bandwidth during the normal backup window. • All destination tapes created by echo copy are in the native tape format, so they can be restored directly from any tape drive or library that is visible to the backup application. When determining whether to use echo copy, remember: • 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 media pools in your backup jobs. • Human error is a factor to keep in mind. With linked media management, any mistakes with the destination library's media will also affect the virtual cartridges. For example, if new tapes are not loaded into the destination library, new, matching virtual tapes will not be created. Subsequent backups will fail because the virtual tapes present are protected. • The backup application will not be aware of any copy failures. Implementation Echo Copy Pools An echo copy pool is used to define which destination library slots are to be echoed by a specified virtual library. Automigration then monitors the echo copy pool slots to detect cartridge loads and ejects in the destination library. Automigration automatically synchronizes the virtual cartridges to the destination cartridges, creating matching virtual cartridges as needed. When new destination tapes are loaded, automigration scans them, and reads the backup application headers. It then creates matching virtual cartridges in the virtual library specified for the echo copy pool the physical tape is in. See Figure 60. HP StorageWorks VLS and D2D Solutions Guide 141

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Echo Copy Concepts
Echo copy essentially acts as a transparent disk cache to the physical library, so that echo copy jobs
can be performed at times other than the peak backup window. Once automigration is set up, echo
copy operations are automatic and seamless to the user. During the normal backup window, the
backup application writes to virtual cartridges. Each virtual cartridge that pertains to an echo copy
pool has header information that matches a physical cartridge in the tape library. During the
user-established automigration window, data migrates from each virtual cartridges to its matching
physical cartridge.
Echo copy is managed through the automigration software, not the backup application. For that
reason:
•
The destination library is not visible to the backup application, so it does not need licensing.
•
Copy traffic is no longer routed through the SAN.
•
Maximizes performance of high-speed tape drives by freeing bandwidth during the normal backup
window.
•
All destination tapes created by echo copy are in the native tape format, so they can be restored
directly from any tape drive or library that is visible to the backup application.
When determining whether to use echo copy, remember:
•
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 media pools in your backup jobs.
•
Human error is a factor to keep in mind. With linked media management, any mistakes with the
destination library's media will also affect the virtual cartridges. For example, if new tapes are
not loaded into the destination library, new, matching virtual tapes will not be created. Subsequent
backups will fail because the virtual tapes present are protected.
•
The backup application will not be aware of any copy failures.
Implementation
Echo Copy Pools
An echo copy pool is used to define which destination library slots are to be echoed by a specified
virtual library. Automigration then monitors the echo copy pool slots to detect cartridge loads and
ejects in the destination library. Automigration automatically synchronizes the virtual cartridges to the
destination cartridges, creating matching virtual cartridges as needed. When new destination tapes
are loaded, automigration scans them, and reads the backup application headers. It then creates
matching virtual cartridges in the virtual library specified for the echo copy pool the physical tape is
in. See
Figure 60
.
HP StorageWorks VLS and D2D Solutions Guide
141