Copy To Tape Using D2D Tape Offload; Copy To Remote Disk Backup Device Using Replication - HP StorageWorks 12000 - Virtual Library System EVA Gateway Manual

virtual tapes will not be created. Subsequent backups will fail because the virtual tapes present
are protected.
NOTE:
Automigration echo copy is not suitable for use with deduplication because:
• You cannot use echo copy to create archive tapes from the replication target device because these
must have a different barcode, retention time, cartridge size, and contents. They must be created
by another instance of the backup application. (See
Target.)
• Echo copy acts as a disk-cache to the physical tapes, so when physical tapes are ejected from the
library (for example, to be sent off-site) this also ejects the matching virtual cartridges into the
Firesafe; they are disabled in the deduplication system.
• Echo copy only copies whole cartridges and because the size of deduplicated virtual cartridges
is generally 50-200 GB, a large amount of tape capacity would be wasted if LTO3 or LTO4
physical tapes were used.

Copy to Tape using D2D Tape Offload

You can offload cartridges to physical tape using a tape drive or library that is physically attached
to the D2D system via SAS or pSCSI and is not visible to the backup application. This solution offers
the following benefits:
• Tape offload can be conducted during normal working hours without affecting network performance
because no data is sent over the network during the offload.
• Cartridges can be offloaded at the maximum read performance for a virtual library which makes
this process relatively fast.
• Offloaded cartridges are in backup application format, so you can use it to directly restore data
using a tape drive attached to a media server if necessary.
However, you must take into account a number of shortfalls of this configuration:
• The backup application cannot track the physical cartridges because it played no part in their
creation. A cartridge copied by the D2D is only valid for as long as the virtual cartridge remains
current; if the virtual cartridge is modified (overwritten or appended), the physical cartridge content
no longer has a valid entry in the backup application database. However, you could still use it
for disaster recovery if you lost the backup application database. Creating long rotation schemes
where cartridges are overwritten infrequently works well with this model.
• Even with the scheduling features provided in the D2D GUI, offloads are hard to accurately
schedule to coincide with completion of the original backup.
Do not use physical tape offload as a way to free up space on the D2D by removing the virtual
cartridge after an offload. Doing this will not save space due to the deduplication effect and will result
in backup application database entries becoming invalid. In addition, HP does not recommend using
physical media to extend the retention period of a backup (i.e., keeping a physical cartridge beyond
the point where its associated virtual cartridge has been overwritten) because the backup application
database will become inconsistent with the backup on tape.

Copy to Remote Disk Backup Device using Replication

Deduplication can automate the off-site process and enable disaster recovery by providing site to site
deduplication-enabled replication at a lower cost. Because deduplication knows what data has
changed at a block or byte level, replication becomes more intelligent and transfers only the changed
Creating Archive Tapes from the Replication
HP StorageWorks VLS and D2D Solutions Guide 43