HP Serveur lame HP ProLiant BL465c Gen8 - Manual (Page 68)

If logical errors, such as those caused by viruses, occur on both the active side and the passive side,
the data is restored from the tape device to secondary volume 1, and then from secondary volume 1
to primary volume 1. The restored data is then applied to primary volume 2 via seed processing.
Comparison of DAG configurations
The following table compares the four types of DAG configurations that use Application Agent. Refer
to this table when setting up your system.
Table 2 Comparison of DAG configurations
Configuration 4 Configuration 3 Configuration 2 Configuration 1 Item
Backup and restore
operations are still
available if an error
occurs on one backup
volume. Backup and
restore operations are
not available if an er-
ror occurs on one
backup server.
Backup and restore
operations are still
available if an error
occurs on one
backup server or on
one backup volume.
If an error occurs on the backup server or the
backup volume, backup and restore operations
are not available.
Fault toler-
ance
More backup servers and backup volumes
are required than in Configuration 1 and
Configuration 2. Fewer backup servers and backup volumes
are required than in Configuration 3 and
Configuration 4.
Cost
The verification time
is double that of the
other configurations
because two backup
volumes are used and
only one backup
server manages these
volumes. However,
you can specify the
VERIFY_PARAL-
LEL_COUNT paramet-
er to perform verifica-
tion processing in
parallel to shorten the
time required.
Verification time is
shorter than in Config-
uration 4, although
two backup volumes
are used, because
each backup volume
is managed by a dif-
ferent backup server.
Verification time is shorter than in Configura-
tion 4 because only one backup volume is
used. Time required
for verifica-
tion
Legend:
Configuration 1: Configuration in which the active mailbox database copy is backed up and re-
stored
Configuration 2: Configuration in which the passive mailbox database copy is backed up and
restored
Configuration 3: Configuration in which the active mailbox database copy and the passive
mailbox database copy are backed up and restored by different backup servers
Configuration 4: Configuration in which the active mailbox database copy and the passive
mailbox database copy are backed up and restored by the same backup server
Application Agent system configurations 68