HP OpenVMS System Manager's Manual, Volume 2:...

Managing DECdtm Services

Creating Transaction Logs

Checking Whether a Transaction Log Is Too Small

Monitoring Transaction Performance  

How to Perform This Task

1. Monitor transactions, using the MONITOR TRANSACTION command:MONITOR TRANSACTION/SUMMARY[=file-spec]/ENDING=time/NODE=(nodename,...)where:

   file-spec	is the file specification of the summary file. Information about transactions is summarized and recorded in the summary file. If you omit the file specification, the information is recorded in MONITOR.SUM in your default directory.
   time	is the time that the monitoring session ends.
   nodename	is the name of a node. In an OpenVMS Cluster, list all the nodes in the cluster.

   
   

   For the best results, monitor transactions for a day at a time.
   
   You can monitor transactions in batch mode by including the MONITOR TRANSACTION command in a command procedure.
   
   For a full description of the MONITOR TRANSACTION command, refer to the HP OpenVMS System Management Utilities Reference Manual.

2. Examine the summary file.
   
   The summary file contains values for a number of different data items. Note the following values for each node:
   • Average end rate. This is the average number of transactions completed per second.
   
   
   
   • Average completion rates. These are the average numbers of transactions completed in the following times:

     Less than 1 second

     Between 1 and 2 seconds

     Between 2 and 3 seconds

     Between 3 and 4 seconds

     Between 4 and 5 seconds

     More than 5 seconds

   Make a note of these values.
3. Compare the results from this monitoring session with the results from previous sessions.
   
   For the same work load, the rate and duration of transactions should remain about the same. Indications of performance deterioration are:
   • The average end rate decreases
   
   
   
   • The average duration increases
     
     To find out whether the average duration of transactions has increased, compare the average completion rates. If a greater proportion of the transactions takes longer to complete, the average duration of transactions has increased.
   Note any trends over a number of monitoring sessions. Variations from one monitoring session to the next are probably due to variations in work load.
   
   If you suspect that transaction performance has deteriorated on any node, check whether its transaction log is too small (see Checking Whether a Transaction Log Is Too Small).
   
   If the transaction log is big enough, but transaction performance still deteriorates, tuning the system might be necessary. Refer to OpenVMS Performance Management for information about tuning your system.

Example

This example shows how to monitor transaction performance on an OpenVMS Cluster that consists of two nodes whose SCSNODE names are BLUE and RED.

Monitor transactions on nodes BLUE and RED for one day:

$ MONITOR TRANSACTION/SUMMARY=DISK$LOG1:[LOGFILES]TRANSACTIONS.SUM -
_$ /ENDING="+1-"/NODE=(BLUE,RED) 

                   DISTRIBUTED TRANSACTION STATISTICS
                             on node BLUE         From: 16-OCT-2000 14:23:51
                                SUMMARY           To:   17-OCT-2000 14:23:51
                                   CUR        AVE        MIN        MAX
 
Start Rate                       49.02      43.21      31.30      49.02
Prepare Rate                     48.70      43.23      30.67      48.70
One Phase Commit Rate             0.00       0.00       0.00       0.00
Total Commit Rate                48.70      43.19      31.30      48.70
Abort Rate                        0.00       0.00       0.00       0.00
End Rate                         48.70      43.19      31.30      48.70
Remote Start Rate                 0.00       0.00       0.00       0.00
Remote Add Rate                   0.00       0.00       0.00       0.00
 
Completion Rate    0-1           21.42      13.57       0.63      21.42
 by Duration       1-2           25.97      29.15      24.59      33.87
 in Seconds        2-3            1.29       0.47       0.00       4.47
                   3-4            0.00       0.00       0.00       0.00
                   4-5            0.00       0.00       0.00       0.00
                    5+            0.00       0.00       0.00       0.00
 
                              SUMMARIZING
 
DISTRIBUTED TRANSACTION STATISTICS		   
                             on node RED          From: 16-OCT-2000 14:23:52
                                SUMMARY           To:   17-OCT-2000 14:23:52
 
.
.
.

• Average end rate.
  
  For node BLUE, the average end rate is 43.19 transactions per second.



• Average completion rates.
  
  For node BLUE, the average completion rates are as follows:
  
  

  13.57 transactions completed in 0 to 1 seconds

  29.15 transactions completed in 1 to 2 seconds

  0.47 transactions completed in 2 to 3 seconds

Compare the results from this monitoring session to those of previous sessions:

Session	End Rate	Completion Rates
		0-1 Secs	1-2 Secs	2-3 Secs
Session	End Rate	Completion Rates
		0-1 Secs	1-2 Secs	2-3 Secs
June	42.13	12.98	28.13	1.02
July	38.16	10.35	25.80	2.01
August	43.19	13.57	29.15	0.47

The results for node BLUE show no signs of deteriorating performance.

Creating Transaction Logs

Checking Whether a Transaction Log Is Too Small