Garbage Collection

Garbage collection is the process of reviewing the Proxy Server cache and removing old (stale) files. Garbage collection is a resource-intensive process, therefore you may need to tune some garbage collection settings to improve its performance.

The following parameters provide the ability to fine-tune the garbage collection process. You can view or modify these parameters on the Tune Garbage Collection form, which is located by choosing Tune GC under the Caching tab of the Server Manager.

This section contains the following topics:

• The gc hi margin percent Variable

• The gc lo margin percent Variable

• The gc extra margin percent Variable

• The gc leave fs full percent Variable

The gc hi margin percent Variable

The gc hi margin percent variable controls the percentage of the maximum cache size that, when reached, triggers garbage collection.

This value must be higher than the value for gc lo margin percent.

The valid range for gc hi margin percent is 10 to 100 percent. The default value is 80 percent (trigger garbage collection when the cache is 80 percent full).

The gc lo margin percent Variable

The gc lo margin percent variable controls the percentage of the maximum cache size that the garbage collector targets.

This value must be lower than the value for gc hi margin percent.

The valid range for gc lo margin percent is 5 to 100 percent. The default value is 70 percent (target at 70 percent full cache after garbage collection).

The gc extra margin percent Variable

If the garbage collection is triggered by a reason other than the partition’s size getting close to the maximum allowed size (gc hi margin percent), the garbage collector will use the percentage set by the gc extra margin percent variable to determine the fraction of the cache to remove.

The valid range for gc extra margin percent is 0 to 100 percent. The default value is 30 percent (remove 30 percent of existing cache files).

The gc leave fs full percent Variable

The gc leave fs full percent value determines the percentage of the cache partition size below which garbage collection will not go. This value prevents the garbage collector from removing all files from the cache if some other application is monopolizing the disk space.

The valid range for gc leave fs full percent is 0 (allow total removal) to 100 percent (remove nothing). The default value is 60 percent (allow the cache size to shrink to 60 percent of current).