The calculate overhead dialog lets user know how much of the allocated size will be utilized in overhead. For example, if you want to create a cache of 1MB, there is an internal overhead of 0.02MB. In order to create a cache with 1MB, you must specify 1.02MB so that after overhead, the usable cache size will be 1MB.
Changing the size or type of a named cache
Select the cache icon, then select File | Properties.
Select the Configuration tab.
Select one of the options:
To modify a cache to hold both data and transaction log information, select “Stores Data and Log Pages.”
To modify a cache to hold only transaction log information, select “Only Stores Log Pages.” This option is not available if the cache has any databases, indexes, or tables bound to it. To change a cache to a log-only cache, first unbind any nonlog bound objects from it. You cannot change the default cache to a log-only cache.
To change the size, edit the Currently Configured text box. The new size is subject to the following constraints:
When you reduce the size, all space is removed from the default buffer pool. You cannot specify a size that reduces the default pool to less than the 512K minimum. For details, see “Defining buffer pools”.
When you increase the size, all new space is added in the default buffer pool. You cannot increase the size to an amount that exceeds the value in the Maximum Size box.
Because creating a cache involves some overhead, the
actual amount of available memory is slightly less than the amount
in the Maximum Size box.
Click OK or Apply. For the new specifications to take effect, you must stop and restart Adaptive Server.
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