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Table 1. Parameters in the control file

Parameter start_mode


Determines whether Optimizer is enabled or disabled whenever Optimizer is launched, such as after the service processor is rebooted.

s w a p _ m o d e

Controls whether Optimizer should automatically swap volumes as soon as it finds swaps that

would improve performance. If Optimizer is enabled in AUTO swap mode, each day it will make up to the number of swaps specified by the swap_rate parameter, under control of the swap time window settings. If Optimizer is enabled in USER_OK swap mode, it will generate lists of swap suggestions approximately once an hour, and then wait for the user to approve the swap list before proceeding.


Controls how many swaps Optimizer can perform simultaneously (up to four). The actual value should reflect the number of volumes that will be swapped simultaneously. The acceptable values are from two (a single pair swapped) to eight (four pairs swapped) Optimizer swaps.


Sets the maximum number of swaps that Optimizer is allowed to make in a single day. This parameter is only relevant if swap_mode is set to AUTO. Note that reflects the total number of volumes to be swapped in a day. A value of 24 would allow 12 pairs of volumes to be swapped in a day.


Specifies the amount of samples required initially before a recommendation will be made. You should make sure that the values you specify are long enough (usually a week) for Optimizer to establish a good characterization of your typical workloads. This parameter is expressed in hours. Keep in mind that the Optimizer statistics database holds about 14 days worth of data.


Specifies how far back in time Optimizer should consider when the optimization algorithm is run. Be careful not to make this value too large or you may include data that is so old it is no longer representative of your current workloads. This parameter is expressed in hours.

The following control file sets up Optimizer to analyze data from the previous seven days and to start figuring out swap suggestions after three days of collecting data. It also sets Optimizer to User Approved mode and sets the maximum number of simultaneous swaps to eight (four pairs of hypervolumes).

s e t c o n t r o l _ p a r m s s t a r t _ m o d e = A U T O min_perf_period=72, workload_period=168, swap_mode=USER_OK, max_simult_swaps=8, swap_rate=50; ,

Setting User Approved mode

User Approved mode allows you to see what swaps will occur before they take place. To switch Optimizer into User Approved mode, use the set control_parms swap_mode=USER_OK; line in the command file. Once this is set, Optimizer recalculates a swap list about once every hour as long as samples have been collected for the specified minimum performance period. At any time, the latest swap list can be retrieved using the symoptmz show –swap_list command. The swap list can then be approved or declined using the following syntax in the command file:

set swap <APPROVE | DECLINE> [begin_at=<time_val>,]

EMC Symmetrix Optimizer A Detailed Review


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