GBP Coupling Facility Cache Structure Statistics Summary
This panel shows a summary of the DB2 group buffer pool (GBP) coupling facility cache structure statistics. It can be displayed in S mode or in G mode. In S mode, a summary of the Group Buffer Pools of the current member is displayed. In G mode, a summary of the Group Buffer Pools of all members is displayed.
________________ ZS254 VTM O2 V540./I SN13 S 02/12/13 5:32:01 2
> Help PF1 Back PF3 Up PF7 Down PF8 Zoom PF11
> R.O
>
> GBP COUPLING FACILITY CACHE STRUCTURE STATISTICS SUMMARY
S254
+ Collection Interval: REALTIME SNAPTIME: 02/12/13 04:32:01.72
+
+ GBPName ReadMiss WriteMiss XIDirRClm CastOut DirEntry DataEnty TotChnge
+ -------- --------- --------- --------- --------- --------- --------- --------
+ GBP0 0 0 0 10923 316 2 0
+ GBP1 0 0 0 0 0 0 0
+ GBP2 0 0 0 0 0 0 0
+ GBP8K0 0 0 30727 8 1 0 0
+ TOTAL 0 0 30 10 0 0 0
===============================================================================
________________ ZS254 VTM O2 V540./I SN13 G 02/12/13 5:32:40 2
> Help PF1 Back PF3 Up PF7 Down PF8 Zoom PF11
> R.O
>
> GBP COUPLING FACILITY CACHE STRUCTURE STATISTICS SUMMARY
S254
+ Collection Interval: REALTIME SNAPTIME: 02/12/13 04:32:40.05
+
+
+ DSG Member: SN13
+ GBPName ReadMiss WriteMiss XIDirRClm CastOut DirEntry DataEnty TotChnge
+ -------- --------- --------- --------- --------- --------- --------- --------
+ GBP0 0 0 0 10923 316 2 0
+ GBP1 0 0 0 0 0 0 0
+ GBP2 0 0 0 0 0 0 0
+ GBP8K0 0 0 30727 8 1 0 0
+ TOTAL 0 0 30 10 0 0 0
+
+ DSG Member: SN12
+ GBPName ReadMiss WriteMiss XIDirRClm CastOut DirEntry DataEnty TotChnge
+ -------- --------- --------- --------- --------- --------- --------- --------
+ GBP0 0 0 0 10923 316 2 0
+ GBP8K0 0 0 30727 8 1 0 0
+ TOTAL 0 0 30 10 0 0 0
+
+ DSG Member: SN11
+ GBPName ReadMiss WriteMiss XIDirRClm CastOut DirEntry DataEnty TotChnge
+ -------- --------- --------- --------- --------- --------- --------- --------
+ GBP0 0 0 0 10923 316 2 0
+ TOTAL 0 0 0 10 0 0 0
+
+ DSG Member: SN14
+ GBPName ReadMiss WriteMiss XIDirRClm CastOut DirEntry DataEnty TotChnge
+ -------- --------- --------- --------- --------- --------- --------- --------
+ GBP0 0 0 0 10923 316 2 0
+ GBP1 0 0 0 0 0 0 0
+ GBP8K0 0 0 30727 8 1 0 0
+ GBP16K0 0 0 0 0 0 0 0
+ TOTAL 0 0 30 10 0 0 0
=============================================================================== Navigation
You can browse details of a group buffer pool or the TOTAL values by moving the cursor to the appropriate line in the panel and pressing PF11 (Zoom).
- G mode in S mode or vice versa, replace the letter S with G or vice versa.
- other members of the data sharing group or other DB2 subsystems that are monitored by the current server, type over the Db2 SSID.
- the details of a particular GBP cache structure statistics, move the curser to the GBP of your choice and click F11 (Zoom).
- other topics, use the PF keys.
Fields
- GBPName
- The name of the group buffer pool.
- ReadMiss
- 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.
- WriteMiss
- 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.
- XIDirRClm
- 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
- 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.
- DirEntry
- 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.
- DataEntry
- 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.
- TotChnge
- 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.