Scenario 4 - Fourth Request

The user issues IXLCACHE REQUEST=WRITE_DATA to write a new and changed data item and assigns it to storage class 1.

Environment

Environment at the time of the user action:

No free storage available in cache structure.
There is enough reclaimable storage in each of the three storage classes to satisfy the request.

System Response

The system cannot reclaim storage from storage classes 1 or 2 because the vector counter indicates that the entries are 0. The system reclaims storage from storage class 3 and allocates it to the new data item. It subtracts 1 from the reclaim counter for storage class 3 in the vector.

Vector Counts after the Request

On the next request, the system can perform storage reclaims for data items assigned to storage class 1 as follows:

From storage class 1: 0 reclaims
From storage class 2: 0 reclaims
From storage class 3: 0 reclaims (Changed after this request)

The system has now made one iteration through the reclaim vector and subtracts 1 from the repeat factor of 2 specified on IXLCACHE. The system resets the vector to the original values for each storage class as follows:

From storage class 1: 2 reclaims
From storage class 2: 0 reclaims
From storage class 3: 1 reclaims

It can make another iteration through the vector and repeat the reclaim process based on the values. When it completes a second time, it subtracts 1 from the current repeat counter value (1) for a value of zero. When the counter equals 0, the system deactivates the vector and uses the default reclaim algorithm for storage class 1.