Average device response times

The Average Device Response Times section of the Performance Data window displays the read and write times for the copy, refresh, copy cylinder, refresh cylinder, and estimated sync time operations.

The Average Device Response Times section provides the following information:

  • Volume Refresh and Synchronization Information displays the number of tracks and cylinders that are refreshed and synchronized for that specific migration.
  • The Sync Goal in Seconds is the value that was set at job submission or modified through the TDMF Monitor.
  • Estimated Sync Time Required in Seconds is the calculated value for the synchronization phase. This value should be less than the total Estimated Sync Time (read and write) that is displayed in the Average Device Response Time section.
  • The last display is the start and end times for each phase and the total elapsed time for the copy, refresh, and synchronization phases of the volume pairing.
    Note: The estimated synchronization time is normally the sum of the predicted synchronization read and write times. However, if the Full Speed Copy option was requested, the read and write operations overlap, so the estimate is the greater of the two times, rather than their sum.

The following figure shows an example of average device response times.

Figure 1. Performance Data window - average device response times
Average Device Response Time by Operation:      Read           Write
 Copy                                           00.018 Secs    00.034 Secs
 Refresh                                        00.019 Secs    00.035 Secs
 Copy Cylinder                                  00.270 Secs    00.510 Secs
 Refresh Cylinder                               00.285 Secs    00.525 Secs
 Estimated Sync Time                            03.230 Secs    05.925 Secs
Refresh and Synchronization Information.        Refresh        Sync.
 Refresh and Synchronization I/O counts
 Tracks                                         00123          00020
 Cylinders                                      00017          00010
 Synchronization Goal in Seconds         :                       005
 Estimated Sync time required in seconds :                       010

Each volume in the session is listed in the order that is specified on the MIGRATE or REPLICATE control record in the Master batch job. Therefore, the previous five windows are displayed for each volume. To view performance data for a specific volume within the session, you can use the find command or scroll through the windows.

If you want to see information about a different session, change the entry on the ComDataSet line at the top of the window.

Note: Full Speed Copy Effect - Using the Full Speed Copy option can reduce the elapsed time of the copy subphases of each volume that is being migrated. Real memory is reduced for an extra data buffer so that read and write I/O operations overlap or take place simultaneously. The impact of using Full Speed Copy is reflected in the average device response times. For example, if the device service times of the read and write cylinder operations for the copy and refresh phases were equal (510 milliseconds in the previous example), if you use the Full Speed Copy option it would decrease the required time for I/O operations by half. The migration completes in about half the usual elapsed time