Monitor elements for viewing cluster caching facility memory usage
The IBM® Db2® pureScale® Feature provides a number of monitor elements that report on cluster caching facility memory usage.
Monitor elements
The following monitor elements provide information about how various CF memory heaps are allocated and used:- configured_cf_gbp_size - Configured cluster caching facility group buffer pool size monitor element
- current_cf_gbp_size - Current cluster caching facility group buffer pool size monitor element
- target_cf_gbp_size - Target cluster caching facility group buffer pool size monitor element
- configured_cf_lock_size - Configured cluster caching facility lock size monitor element
- current_cf_lock_size - Current cluster caching facility lock size monitor element
- target_cf_lock_size - Target cluster caching facility lock size monitor element
- configured_cf_mem_size - Configured cluster caching facility memory size monitor element
- current_cf_mem_size - Current cluster caching facility memory size monitor element
- configured_cf_sca_size - Configured cluster caching facility shared communications area size monitor element
- current_cf_sca_size - Current cluster caching facility shared communications area size monitor element
- target_cf_sca_size - Target cluster caching facility shared communications area size monitor element
Tip: In all cases, the values reported
for each of these monitor elements is expressed in terms of 4k pages.
So, for example, if you queried the current_gbp_size monitor element, and it returned a value of 350, then the actual
amount of memory currently used for the GBP would be 350 × 4096 bytes
= 1,433,600 bytes.
For most of these types of memory, there
are three monitor elements that you can query that represent different
aspects of how the memory is configured.
Refer to the reference topics
for each monitor element to see what monitoring interfaces you can
use to examine the data associated with that monitor element.- Current
- The current memory size (for example, current_cf_gbp_size, or current_cf_mem_size) represents the amount of that type of memory currently in use by the system.
- Configured
- The configured memory size (for example, configured_cf_sca_size, configured_cf_mem_size) represents the total amount of that type of memory that is currently configured by the database as the maximum. The value for current memory can never exceed that of configured memory.
- Target
- The target memory size (for example, target_cf_sca_size) represents a new configured maximum value for that type of memory. Usually, the target size is the same as the configured size. However, if the target and configured sizes differ, that means that that particular type of memory is undergoing an online change in its configured size. The process of allocating memory takes place over time. At any point during this resizing process, the configured memory represents the maximum amount of that type of memory that can be used at that specific point in time. Eventually, the configured memory becomes the same as target memory.