HP Storage Mirroring V5 Software - Manual (Page 121)

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Scheduled Transmission Options
The following transmission options are available through the Management Console and the Text Clients. They are user
configurable settings which can occur in any order or combination. The options can be set and then disabled, allowing you to
enable them only when you need to use them.
‹ Storage Mirroring Start Transmission Criteria —When Storage Mirroring is not transmitting data, it places the
information in a queue on the source. When transmission begins, Storage Mirroring sends all of the data from the queue
to the target machine in the same order it was placed on the queue. Through the transmission start criteria you can set
four triggers which initiate the transmission of data from the source to the target.
‹ Transmission Session Start —The transmission session start establishes a date and time of the day to begin
transmitting data. For example, you may want to specify a transmission time that corresponds to a low bandwidth
usage time. Once started, Storage Mirroring will continue to transmit data until the queue is empty or until another
limitation stops the transmission.
‹ Session Interval —The session interval begins transmitting Storage Mirroring data at specified intervals of time. This
option is used in conjunction with Transmission Session Start . For example, if the Session Interval is set to repeat
transmission every 30 minutes and the Transmission Session Start is set to begin transmitting at 10 p.m., if the queue
is emptied at 10:20 the transmission will stop. The start criteria is again met at 10:30 and Storage Mirroring will begin
transmitting any new data in the queue.
‹ Queue Thresholds —If the allocated amount of queue disk space is in use, Storage Mirroring cannot continue to
queue data causing an auto-disconnect and the potential for loss of data. To avoid using the entire queue, you can
configure Storage Mirroring to begin transmitting data to the target when the queue reaches a certain point. This
point can be defined as a percentage of the disk queue that must be in use or the number of bytes in the disk queue.
For example, if you specify 40%, when 40% of the queue is in use, Storage Mirroring initiates the transmission process
and sends the data in the queue to the target machine. The transmission stops when the queue is empty or a Storage
Mirroring stop transmission criteria is met. Or you might set a queue threshold of 500 MB. Storage Mirroring will
wait until there is 500 MB of data in the queue and then begin transmitting the data. Like other start criteria, Storage
Mirroring continues transmitting until the queue is empty or a Storage Mirroring stop criteria is met.
‹ Storage Mirroring Stop Transmission Criteria —There may be instances when Storage Mirroring is currently
transmitting data, but the transmission should be stopped. This might occur at high traffic times when transmitting Storage
Mirroring data might affect network traffic. Through the transmission stop criteria you can set two triggers which stop
the transmission of data from the source to the target.
‹ Time Limit —The time limit specifies the maximum length of time for each transmission period. Any data that is not
sent during the specified time limit remains on the source queue. When used in conjunction with the session interval
start option, you can explicitly define how often data is transmitted and how long each transmission lasts.
‹ Byte Limit —The byte limit specifies the maximum number of bytes that can be sent before ending the transmission
session. When the byte limit is met, Storage Mirroring will automatically stop transmitting data to the target. Any
data that still remains waits in the source queue until the transmission is restarted. When used in conjunction with
a session start option, you can explicitly define how much data is being sent at a given time.
NOTE: The transmission options are set for each target machine and cannot be defined separately for each replication
set or source/target combination. This means that all connections to a target will have the same transmission
options despite the source and replication set. For example, if you have two replication sets on the same source
and these replication sets are connected to the same target, any scheduling criteria established for one
connection will also be applied to the other connection.
NOTE: A Transmission Session Start setting will override any other start criteria. For example, if you set the
Transmission Session Start and the Queue Threshold , transmission will not start until you reach the
indicated start time.
NOTE: Storage Mirroring checks the schedule once every second, and if a user defined criteria is met, transmission
will start.
NOTE: The transmission start and stop criteria should be used in conjunction with each other. For example, if you
set the Queue Threshold equal to 10 MB and the Byte Limit equal to 10 MB, a network connection will
be established when there is 10 MB of data in the queue. The data will be transmitted and when the
10 MB Byte Limit is reached, the network connection closes. This is useful in configurations where metered
charges are based on connection time.