DSG GBP CF Statistics attributes

Use these attributes to view the group buffer pool (GBP) coupling facility (CF) statistics of the Data Sharing Group (DSG).

Changed Page Write Hit Counter Secondary GBP The number of successful coupling facility write requests for changed pages (Field name: QW02542W).

Changed Page Write Hit Counter This is the number of times a coupling facility write request for a changed page successfully completed (Field name: QW0254WH).

Clean Page Write-Hit Counter This is the number of times a coupling facility write request for a clean page completed successfully (Field name: QW0254WC).

DB2 Subsystem The Db2 subsystem ID.

DB2 Version The DB2 version.

DSG Member Name The Data Sharing Group (DSG) member name.

Data Area Residency Time The data area residency time. This value is the weighted average, in microseconds, of the elapsed time that a data area resides in a group buffer pool before the data area is reclaimed (Field name: QW0254AR).

Directory Entry Residency Time The directory entry residency time. This value is the weighted average, in microseconds, of the elapsed time that a directory entry resides in a group buffer pool before the directory entry is reclaimed (Field name: QW0254ER).

Data Entry Counter of Secondary GBP This is the snapshot value of the number of allocated data entries (Field name: QW02542T).

Data Entry Reclaim Counter This is the number of times a name assignment required that a data page must be reclaimed by the coupling facility (Field name: QW0254TR).

Data Sharing Group The data sharing group name.

Dir Counter for Secondary Group Buffer Pool The directory-entry counter for the secondary group buffer pool. This is the snapshot value of the number of allocated directory entries (Field name: QW02542D).

Directory Entry Reclaim Counter This is the number of times a name assignment required that a directory entry must be reclaimed by the coupling facility (Field name: QW0254DR).

Explicit XI Requests This is the number of times that a request was made to the coupling facility to explicitly cross-invalidate a page. XI signals were sent because the named page was cached in one or more DB2 buffer pools (Field name: QW0254CI).

Global Group Buffer Pool Name The name of the global group buffer pool for which statistics are reported.

Global Group Buffer Pool ID The number of the global group buffer pool for which statistics are reported (Field name: QW0254GN).

Interval Start The start time of this interval.

MVS System ID The MVS identifier.

Number of Allocated Data Entries (snapshot) This is the number of data entries allocated for the coupling facility cache structure (DB2 group buffer pool). Data entries are the actual places where the data page resides. This is a snapshot value and is not affected by whether this is an incremental or cumulative display (Field name: QW0254TE).

Number of Allocated Directory Entries (Snapshot) This is the number of directory entries allocated for the coupling facility cache structure (DB2 group buffer pool). A directory entry contains control information for one database page. A directory entry is used by the coupling facility to determine where to send cross-invalidation signals when a page of data is changed or when the directory entry must be reused. This is a snapshot value and is not affected by whether this is an incremental or cumulative display (Field name: QW0254DE).

Number of Castout Operations Performed This is the number of castout operations performed. Castout is the process of writing pages from the group buffer pool to DASD (Field name: QW0254CC).

Number of Data Entries in Changed State This is the snapshot value of the current number of changed pages. The displayed value of this counter is not affected by whether this is an incremental or cumulative display (Field name: QW0254TC).

Originating System The managed system name of the agent. It is an alphanumeric text string, with a maximum of 32 characters; for example, DB91:SYS1:DB2.

Read Count The total read count (Field name: SW254RDC).

Read Hit Counter This is the number of times that a page was returned on a coupling facility read request (Field name: QW0254RH).

Read Hit Percent The percentage of read hits (Field name: SW254RHR).

Read Miss Directory Hit Counter This is the number of times that a coupling facility read request specified a page for which a directory entry exists, but no data was cached for that page (Field name: QW0254RD).

Read Miss Assignment Suppressed Counter This is the number of times that a coupling facility read request specified a page for which no directory entry exists and no directory entry is created. DB2 does not create a directory entry when it does not need to register the page to the coupling facility for cross-invalidation (XI) because no other DB2 in the group has R/W interest in the page set or partition. This counter also represents the number of times that pages are deregistered due to buffer stealing (Field name: QW0254RS).

Read Miss Cache Full Counter This is the number of times that a coupling facility read request specified a page for which no directory entry exists and no directory entry is created because of a lack of storage in the group buffer pool. A nonzero value in this field indicates that the backing coupling facility cache structure size might be too small to support the current workload (Field name: QW0254RF).

Read Miss Name Assigned This is the number of times that a coupling facility read request specified a page for which a directory entry was created (Field name: QW0254RN).

Total Changed Counter for Secondary GBP This is the snapshot value of the number of allocated data entries that are currently in changed state (Field name: QW02542C).

Write Miss Secondary Cache Full Counter This is the number of coupling facility write requests that could not complete because of insufficient coupling facility storage resources (Field name: QW02542F).

Write Miss Cache Full Counter This is the number of times a coupling facility write request was not completed because of a lack of storage in the group buffer pool. A value in this field indicates that the data page resources of the coupling facility are being consumed faster than the DB2 castout process can free them. For more information about alleviating this condition refer to DB2 data sharing, planning and administration (Field name: QW0254WF).

XI Directory Entry Reclaim Counter This is the number of times a directory entry was reclaimed (stolen) and cross-invalidation (XI) signals had to be sent (that is, the stolen directory entry had registered DB2 interest). A high number might indicate a problem. Check the group buffer pool hit ratio to determine if the lack of directory entries might be causing excessive reads from the group buffer pool (Field name: QW0254XR).