swaps, and allows more time for Optimizer to take the resulting modified workload into consideration for the calculation of the next swap pair.
The maximum number of simultaneous swaps allows Optimizer to perform more than one swap at a time. For each swap pair that may occur simultaneously, the system must be configured with a pair of DRV devices for each size and emulation of volume to be swapped. So, if the user wants four swaps (two pairs) to occur at the same time for 8 GB volumes, then four DRVs (8 GB in size) must be configured. By increasing the maximum number of simultaneous swaps, the system can be optimized much more rapidly.
Eight simultaneous moves (four swaps) proved to be a reasonable option. Since swaps are executed as low priority tasks, the performance impact of multiple swaps is relatively low.
Setting pace and aggressiveness of optimization from SMC
The maximum number of swaps per day and the maximum number of simultaneous swaps can both be set in the Parameters tab of the Optimizer dialog box in the Swap Settings area. In order to change Optimizer parameters, Optimizer must first be stopped.
It is possible to retrieve Optimizer’s activity or error logs. These logs are useful if you want to view an Optimizer error or retrieve past or current state information about Optimizer. The log data is kept on the Symmetrix service processor.
Optimizer keeps log data in memory, not files. You can use the Export icon in the Log tab of the
Optimizer dialog box to save the current log as a file.
Times specified in the log data are in service processor time, with a reference to GMT in parentheses.
Setting logs from SMC
The Log tab (Figure 15) of the Optimizer dialog box lets you retrieve current and past state information on Optimizer activities and errors. To view log information, select either All Activity or Error Log. Specify the beginning of the time period in one of the following ways:
Use the pull-down menu to specify a date and time.
Select Use Optimizer launch as starting date.
Select Use oldest entry as starting date.
Specify the end of the time period by using the pull-down menu or by selecting Ignore ending date. Figure 15 illustrates this feature.
EMC Symmetrix Optimizer A Detailed Review