MONITOR command: Checkpoints-transaction and sub-transaction

Summary

Privileges

System administrator

Function

Enables system administrators to verify the date and time of the last successful checkpoint. Other valuable information, such as the number of timeouts since the successful checkpoint, the number of users preventing checkpoints, and the current size of CHKPOINT, can be displayed.

Syntax

MONITOR {CHECKPOINT | CHKP | SUBTRAN} [USERLIST] [SL] [EVERY n] [SERV]

Where:

CHECKPOINT	Causes basic informational messages for transaction checkpoints to appear. CHKP is the abbreviation for CHECKPOINT.
SUBTRAN	Causes basic information messages for sub-transaction checkpoints as well as transaction checkpoints to appear.
USERLIST	Causes the basic user line to appear for every user who inhibits checkpoints.
SL	Displays the since last statistics.
EVERY n	The number of seconds Model 204 waits after completing a display before beginning the next display.
SERV	Displays server information about the Online. See the MONITOR SERV command as documented in MONITOR: SERVSIZE, LSERVER and server number.

Examples

MONITOR CHECKPOINT MONITOR CHKP USERLIST EVERY 30 MONITOR SUBTRAN USERLIST SL SERV

Usage notes

Monitoring transaction checkpoints

A MONITOR CHECKPOINT command displays the following type of transaction information:

*** M204.2073: LATEST SUCCESSFUL CHECKPOINT COMPLETED AT: yy.ddd hh:mm:ss.th *** M204.2074: n CHECKPOINTS HAVE SINCE TIMED OUT *** M204.2075: n RECORDS CURRENTLY IN ACTIVE CHKPOINT STREAM *** M204.2076: n CHECKPOINTS CURRENTLY IN CHKPOINT STREAM *** M204.2077: n USERS CURRENTLY INHIBITING CHECKPOINTS *** M204.2692: n IS HIGHEST NUMBER OF CHKP RECORDS

A MONITOR CHECKPOINT USERLIST command displays a basic user line for every user that currently inhibits checkpoints. The following type of transaction information is displayed, where the basic MONITOR display is given for only those users currently inhibiting checkpoints:

*** M204.2073: LATEST SUCCESSFUL CHECKPOINT COMPLETED AT yy.ddd hh:mm:ss.th *** M204.2074: n CHECKPOINTS HAVE SINCE TIMED OUT *** M204.2075: n RECORDS CURRENTLY IN ACTIVE CHKPOINT STREAM *** M204.2076: n CHECKPOINTS CURRENTLY IN CHKPOINT STREAM *** M204.2077: n USERS CURRENTLY INHIBITING CHECKPOINTS *** M204.2692: n IS HIGHEST NUMBER OF CHKP RECORDS *** M204.2078: USERS CURRENTLY INHIBITING CHECKPOINTS ARE: USER SVR USERID P CUR SLICE AGE FUNC CNCT CPU SEQIO QUE WT FL nn n xxxx n nn n.nnn n xxxx nnn n.nn n xxxx nn nn

Monitoring sub-transaction checkpoints

A MONITOR SUBTRAN command displays the sub-transaction checkpoints followed by transaction checkpoint information, similar to the following:

SUB-TRANSACTION CHECKPOINTING STATUS: DDNAME SUBTU DRTYF RECS RECHWM DRTYBU DRTYFT CDRPGS CDCPGS BLOGPGS BLOGFT ------ ----- ----- ------ ------ ------ ------ ------ ------ ------- ------ CHKPOINT 0 0 0 0 0 0 0 0 0 0 CHKPNTS 0 0 0 0 0 0 0 0 0 0 *** M204.2697: START OF SUB-TRANS CHKP AT: 00.000 00:00:00.00, CHKPOINT *** M204.2698: END OF SUB-TRANS CHKP AT: 00.000 00:00:00.00, CHKPOINT *** M204.2697: START OF SUB-TRANS CHKP AT: 00.000 00:00:00.00, CHKPNTS *** M204.2698: END OF SUB-TRANS CHKP AT: 00.000 00:00:00.00, CHKPNTS *** M204.2073: LATEST SUCCESSFUL CHECKPOINT COMPLETED AT: 05.004 00:46:22.79 *** M204.2074: 0 CHECKPOINTS HAVE SINCE TIMED OUT *** M204.2075: 1 RECORDS CURRENTLY IN CHKPOINT STREAM *** M204.2692: 1007 IS MAXIMUM NUMBER OF CHKPOINT RECORDS

Where:

*DDNAME specifies the DDname associated with stream, CHKPOINT or CHKPNTS, (* indicates the active DDname) and:

Count	Specifies number of...
SUBTU	Sub-transaction updaters
DRTYF	Dirty files participating in sub-trans checkpoints
RECS	6184-byte records in ddname
RECHWM	6184-byte records written to the stream: the high-water mark
DRTYBU	Dirty buffers flushed (written) back to files
DRTYFT	Milliseconds of elapsed time required to flush the buffers
CDRPGS	Real (in-memory) constraints database pages written
CDCPGS	CCATEMP - constraints database pages written
BLOGPGS	Back out log pages copied
BLOGFT	Milliseconds of elapsed time required to copy back out log pages

The MONITOR SUBTRAN command can be expanded to the following forms to provide the previous display plus information on all users inhibiting transaction checkpoints:

MONITOR SUBTRAN USERLIST MONITOR SUBTRAN USERLIST SL MONITOR SUBTRAN USERLIST SL SERV

For more information about the contents of the basic MONITOR display and transaction and sub-transaction checkpoints, see ONLINE monitoring and Checkpoints: Storing before-images of changed pages.