GBP Coupling Facility Cache Structure Statistics
This panel shows detail information about DB2 Group Buffer Pool (GBP) coupling facility cache structure statistics.
Total values are depicted in KB with a scale of 1000.
________________ ZP254 VTM O2 V540./I SN14 02/25/13 14:30:27 2
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> GBP COUPLING FACILITY CACHE STRUCTURE STATISTICS
Z254 SN12 :GBP8K0
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+ Group Buffer Pool Name GBP8K0
+ Explicit XI Counter 0
+ Read Hit Counter 12
+ Read Miss Directory Hit Counter 14040
+ Read Miss Assign Suppressed Counter 7
+ Read Miss Name Assigned Counter 50593
+ Read Miss Cache Full Counter 0
+ Changed Page Write Hit Counter 72
+ Clean Page Write Hit Counter 0
+ Write Miss Cache Full Counter 0
+ Directory Entry Reclaim Counter 47722
+ Data Entry Reclaim Counter 30
+ XI Dir Entry Reclaim Counter 60865
+ Castout Counter 56
+ Directory Entry Counter 1
+ Data Entry Counter 0
+ Total Changed Counter 0
+
+ Secondary Bufferpool
+------------------------------------
+ Changed Page Write Hit Counter 2 0
+ Write Miss Cache Full Counter 2 0
+ Directory Entry Counter 2 0
+ Data Entry Counter 2 0
+ Total Changed Counter 2 0
=============================================================================== Navigation
You can view other GBP data without going back to the summary display panel by replacing the member name and the GBP name.
For additional information about
- data that is related to the member
MBR1of the same data sharing group and the group buffer poolGBP1, replace SN12 :GBP8K0 with MBR1 :GBP1. If the names of the member and the group buffer pool have less than 8 characters, they must be padded with blanks. - other topics, use the PF keys.
Fields
- Group Buffer Pool Name
- The name of the group buffer pool.
- Explicit XI Counter
- The Explicit XI Counter shows the number of times that:
- a request is made to the coupling facility to explicitly cross-invalidate a page
- XI signals are sent because the named page is cached in one or more Db2 buffer pools.
- Read Hit Counter
- The Read Hit Counter shows the number of times that a page is returned on a coupling facility read request.
- Read Miss Directory Hit Counter
- The Read Miss Directory Hit counter shows the number of times that a coupling facility read request specifies a page for which a directory entry exists, however, data is not cached for that page.
- Read Miss Assign Suppressed Counter
- The Read Miss Assignment Suppressed Counter shows the number of times that a coupling facility read request specifies a page for which a directory entry does not exists or is not created. DB2 does not create a directory entry if it does not need to register the page to the coupling facility for cross-invalidation (XI) because no other Db2 in the group has read or write interest in the page set or partition. This counter also represents the number of times that pages are deregistered due to buffer stealing.
- Read Miss Name Assigned Counter
- The Read Miss Name Assigned Counter shows the number of times that a coupling facility read request specifies a page for which a directory entry is created.
- Read Miss Cache Full Counter
- The Read Miss Cache Full Counter shows the number
of times that a coupling facility read request specifies a page for
which a directory entry does not exist or is not created because the
storage in the group buffer pool is insufficient.
A nonzero value in this field indicates that the size of the backing coupling facility cache structure might be too small to support the current workload.
- Changed Page Write Hit Counter
- The Changed Page Write Hit Counter shows the number of times a coupling facility write request for a changed page is completed successfully.
- Clean Page Write Hit Counter
- The Clean Page Write Hit counter shows the number of times a coupling facility write request for a clean page is completed successfully.
- Write Miss Cache Full Counter
- The Write Miss Cache Full Counter shows the number
of times a coupling facility write request is not completed because
the storage in the group buffer pool is insufficient.
The value in this field indicates that the data page resources of the coupling facility are faster consumed than the Db2 castout process can free them. For information about alleviating this condition, see Db2 Data Sharing: Planning and Administration.
- Directory Entry Reclaim Counter
- The Directory Entry Reclaim Counter shows the number of times a name assignment requires that a directory entry is reclaimed by the coupling facility.
- Data Entry Reclaim Counter
- The Data Entry Reclaim Counter shows the number of times a name assignment requires that a data page is reclaimed by the coupling facility.
- XI Dir Entry Reclaim Counter
- The XI Directory Entry Reclaim Counter shows the
number of times a directory is reclaimed (stolen) and cross-invalidation
(XI) signals are sent because the named page is cached in one or more DB2 buffer pools. This means that
the stolen directory entry has registered DB2 interest.
A high number might indicate a problem. Check the hit ratio of the group buffer pool to determine whether the lack of directory entries might be causing excessive reads from the group buffer pool.
- Castout Counter
- The Castout Counter shows the number of castout operations that are performed. Castout is the process of writing pages from the group buffer pool to DASD.
- Directory Entry Counter
- The Directory Entry Counter shows the number of
directory entries that are allocated for the coupling facility cache
structure (Db2 group buffer
pool). A directory entry contains control information for one database
page. The directory entry is used by the coupling facility to determine
where to send cross-validation signals when a page of data is changed
or when the directory entry must be reused.
This value is a snapshot value. It is not affected by an incremental display or a cumulative display.
- Data Entry Counter
- The Data Entry Counter shows the number of data
entries that are allocated for the coupling facility cache structure
(Db2 group buffer pool). The
data entries are the actual places where the data page resides.
This value is a snapshot value. It is not affected by an incremental display or a cumulative display.
- Total Changed Counter
- The Total Changed Counter shows a snapshot value of the current number of changed pages. This value is not affected by an incremental display or a cumulative display.
- Changed Page Write Hit Counter 2
- The Changed Page Write Hit Counter 2 for the secondary group buffer pool shows the number of successfully completed coupling facility write requests for changed pages.
- Write Miss Cache Full Counter 2
- The Write Miss Cache Full Counter for the secondary group buffer pool shows the number of coupling facility write requests that cannot complete because the coupling facility storage resources are insufficient.
- Directory Entry Counter 2
- The Directory Entry Counter for the secondary group buffer pool shows a snapshot value of the number of allocated directory entries.
- Data Entry Counter 2
- The Data Entry Counter for the secondary group buffer pool shows a snapshot value of the number of allocated data entries.
- Total Changed Counter 2
- The Total Changed Counter for the secondary group buffer pool shows a snapshot value of the number of allocated data entries that are currently in changed state.