Analyzing Volume Replicator performance
You can now analyze the Volume Replicator performance through the performance monitor (perfmon), which is a utility that the Windows operating system provides. This utility can be launched by executing the perfmon command.
To be able to monitor the Volume Replicator performance, the performance objects that have been added to perfmon are as follows:
Each of these performance objects includes a set of performance counters, which are used for logging the Volume Replicator performance-related information. For logging information you must create the log file with the required parameters. To do this, right-click the Counter Log from the tree view and select form the menu that appears.
For more information about using the performance monitor, refer to the help that is available from the Help button on the performance monitor console.
Note: |
When setting the properties for a new log file on a system running Windows Server, you must specify an account with administrative privileges to run the log. Otherwise, the log file fails to gather the required information. |
The Volume Replicator Memory object includes the parameters available with the vxmemstat command, whereas the Volume Replicator remote hosts object includes a combination of parameters available with the vxrlink stats command and the vxrlink status.
The Volume Replicator objects can be viewed using the different graphical view options that perfmon provides.
The following types of Volume Replicator objects can be viewed:
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Volume Replicator Remote Host object
Volume Replicator creates the Volume Replicator Remote host object.
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Volume Replicator Memory Object
Volume Replicator creates the Volume Replicator Memory Object.
Table: Performance object counters and their descriptions for Volume Replicator Remote Host object
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Performance Counter Names
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Description |
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Data Transmitted (KB)
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The amount of data that is successfully transmitted to the remote host.
The following table lists the performance object counters with their descriptions for Volume Replicator Remote Host object.
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DCM Usage (%)
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Indicates the percentage of DCM that is used, based on the number of bits marked in the DCM log.
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Delays
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The total amount of delay that has been introduced so far after flow control was enforced.
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Flow Control NW Bytes
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Number of bytes which can be transmitted without imposing flow control measures.
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Flow Control NW Delay
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The delay that is introduced while sending data, so as to enforce flow control.
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Flow Control Timeout
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Indicates a dynamically computed time-out value for the acknowledgement of a message that has already been sent. If no acknowledgement is received within the time-out period, then retransmission is attempted.
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Lost Packets
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Displays the rate at which replication data packets are lost.
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Memory Errors
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Displays the errors due to insufficient memory.
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Round Trip Time (msec)
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Displays the average round-trip time that is required for transmitting and acknowledging the replication messages.
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SRL Requests
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Displays the number of updates pending on the Replicator Log.
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Stream Errors
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Displays the errors due to insufficient bandwidth.
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Used SRL (%)
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Displays the percentage of the Replicator Log used for recording updates or the writes that need to be replicated.
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The following table lists performance counters with their descriptions for Volume Replicator Memory object.
Table: Performance counters and description associated with Volume Replicator Memory Object
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Field Name
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Description |
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Allocated NMCOM Pool (KB)
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Memory that the Secondary allocates to hold the updates that are received from the Primary.
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Allocated READBACK Memory Pool (KB)
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Memory that is allocated for holding updates after reading them from the Replicator Log.
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Allocated VOLIO Memory Pool (KB)
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Memory that is allocated by the Primary to hold the updates for replicating them.
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Used NMCOM Pool (KB)
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Displays the currently used portion of the allocated NMCOM Pool.
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Used READBACK Pool (KB)
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Displays the currently used portion of the allocated READBACK Pool.
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Used VOLIO Memory Pool (KB)
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Displays the currently used portion of the allocated VOLIO memory Pool.
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WaitQ for VOLIO Memory
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Displays the number of updates waiting for free memory in the VOLIO Memory Pool.
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