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.