IFCID 255 - Buffer Refresh Due to XI

This topic shows detailed information about Record Trace - IFCID 255 - Buffer Refresh Due to XI.

This record is written when a buffer refresh was caused by the cross invalidation (XI) of a data page in the group buffer pool. Cross invalidation occurs when a Db2 member of a data sharing group updates a data page and writes the newly changed page to the group buffer pool. All Db2 members that have this data page cached in their buffer pools are notified that the page was invalidated. If a member needs that data page, it must be refreshed.

DBID:       NO   PIECE NUMBER:   X'00'
OBID: 4          PAGE NUMBER :   X'000002'
BPID:   0        ACE TOKEN   :   N/P
TYPE: SYNCH      FROM: GBPOOL

DBID

The database ID. Deduced from the Db2 fields QW0255DB, QW0105DN or QW0107DN.

When present, the database name is shown, otherwise the decimal identifier from QW0225DB is shown or N/A when this value is 0.

Field Name: RT0255DB

PIECE NUMBER

The data set number of the page set.

Field Name: QW0255PN

OBID

The object ID. Deduced from the Db2 fields QW0255OB, QW0105TN or QW0107TN.

When present, the name of the object is shown, otherwise the decimal identifier from QW0142OB is shown or N/A if this value is 0.

Field Name: RT0255OB

PAGE NUMBER

The relative page number within the data set.

Field Name: QW0255PG

BPID

The internal buffer pool ID.

Field Name: QW0255BP

ACE TOKEN

Ace token of the requester. This address ties the coupling facility read requests for prefetch to the allied agent or database access thread.

Field Name: QW0255AC

TYPE

Indicates whether the buffer refresh was synchronous or asynchronous.

Field Name: QW0255AS

FROM

Indicates whether data was returned from the group buffer pool or DASD.

Field Name: QW0255DR