HP OpenView Storage Mirroring User Guide (360226-002, May 2004)

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! Data Transmission
Data Transmission
Storage Mirroring’s replication and mirroring processes place replication set data on queues on the source and the
transmission process sends the data from the source to the target. There are three methods for transmitting the Storage
Mirroring data:
! Real-time transmission—Storage Mirroring data is continuously transmitted to the target machine. Although the data
may be queued if the network or target machine is slow, the data is transmitted as soon as possible. This is the default
transmission setting.
! Scheduled transmission—Storage Mirroring data is transmitted to the target machine when event driven or scheduling
criteria is met. Storage Mirroring maintains the source/target connection as seen in the Storage Mirroring clients, but the
transmission of data is delayed until the event driven or scheduling criteria is met. The mirror and replication data is
queued until the transmission begins.
! Manual transmission—Storage Mirroring data is transmitted to the target when the network administrator manually
initiates the transmission. Storage Mirroring maintains the source/target connection as seen in the Storage Mirroring
clients, but the transmission of data is delayed until the network administrator manually initiates the process. The mirror
and replication data is queued until the transmission begins.
For each type of transmission, real-time, scheduled, or manual, bandwidth limitations are available to restrict the amount of
network bandwidth used for Storage Mirroring data transmissions.
Bandwidth Limitations
For each type of transmission, real-time, scheduled, or manual, bandwidth limitations are available to restrict the amount of
network bandwidth used for Storage Mirroring data transmissions. The network administrator specifies a percentage of
bandwidth that is available or an absolute bandwidth limit for Storage Mirroring transmissions and Storage Mirroring never
exceeds that allotted amount. The bandwidth not in use by Storage Mirroring is available for all other network traffic.
Real-Time and Manual Transmission
Real-time transmission is the default Storage Mirroring setting. When Storage Mirroring is mirroring and replicating, data is
continuously sent to the target machine. The only way to stop the transmission of data is to manually intervene. Manual
intervention would again be required to restart the transmission.
Scheduled Transmission
Mirror and replication data can be held in a queue until scheduling criteria that you establish has been met. When any of the
scheduling options are met, transmission to the target is started. The transmission can also be stopped by using scheduling
criteria.
Scheduled transmission options can be toggled on and off, allowing you to enable them only when you need to use them.
NOTE: You can also pause the execution of operations on the target rather than modifying how the data is transmitted
from the source.
NOTE: You can stop or pause the transmission of data to the target machine. In both cases, Storage Mirroring queues
data on the source. The difference between these two settings is the effect on the network connection. When
you stop the transmission of data, the network connection between the source and target is terminated and a
new connection will have to be made to restart the transmission. When you pause the transmission of data,
the network connection between the source and target is maintained and can be restarted with the same
connection information as when the pause was made.
NOTE: Storage Mirroring checks the schedule once every second, and if a user-defined criteria is met, transmission
will start or stop, depending on the option specified.