Integer 

Dynamic. Scope = ALTER SYSTEM. 

10 

Any positive integer 

Multiple instances can have different values. 

GC_DEFER_TIME is an Oracle Parallel Server parameter that specifies the time (in 100ths of a second) that the server waits, or "defers," before responding to forced-write requests for hot blocks from other instances. Specifying the GC_DEFER_TIME parameter makes it more likely that buffers will be properly cleaned out before being written. Doing so makes the buffers easier for other instances to read and also improves the chance of hot blocks being used multiple times within an instance between forced writes.

Setting the value to 0 disables the feature. In this case Oracle does not defer forced-write requests at all.