View source for MONITOR command: Checkpoints-transaction and sub-transaction

==Summary==
<dl>
<dt>Privileges
<dd>System administrator
<dt>Function
<dd>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.
</dl>

==Syntax==
<p class="syntax"><b>M</b>ONITOR {CHECKPOINT | CHKP | SUBTRAN} [USERLIST] [SL] [EVERY <span class="term">n</span>] [SERV]
</p>
 
Where:
<table> 
<tr>
<th><var>CHECKPOINT</var></th>
<td>Causes basic informational messages for transaction checkpoints to appear. <var>CHKP</var> is the abbreviation for <var>CHECKPOINT</var>.</td>
</tr>
 
<tr>
<th><var>SUBTRAN</var></th>
<td>Causes basic information messages for sub-transaction checkpoints as well as transaction checkpoints to appear.</td>
</tr>
 
<tr>
<th><var>USERLIST</var></th>
<td>Causes the basic user line to appear for every user who inhibits checkpoints.</td>
</tr>
 
<tr>
<th><var>SL</var></th>
<td>Displays the since last statistics.</td>
</tr>
 
<tr>
<th><var>EVERY</var> n</th>
<td>The number of seconds <var class="product">Model&nbsp;204</var> waits after completing a display before beginning the next display.</td>
</tr>
 
<tr>
<th><var>SERV</var></th>
<td>Displays server information about the Online. See the <var>MONITOR SERV</var> command as documented in [[MONITOR command: SERVSIZE, LSERVER and server number|MONITOR: SERVSIZE, LSERVER and server number]].</td>
</tr>
</table>

==Examples==
<p class="code">MONITOR CHECKPOINT
MONITOR CHKP USERLIST EVERY 30
MONITOR SUBTRAN USERLIST SL SERV
</p>

==Usage notes==

====Monitoring transaction checkpoints====
<p>
A <code>MONITOR CHECKPOINT</code> command displays the following type of transaction information: </p>

<p class="code">*** M204.2073: LATEST SUCCESSFUL CHECKPOINT COMPLETED AT: <i>yy.ddd hh:mm:ss.th</i>
<b></b>*** M204.2074: <i>n</i> CHECKPOINTS HAVE SINCE TIMED OUT
<b></b>*** M204.2075: <i>n</i> RECORDS CURRENTLY IN ACTIVE CHKPOINT STREAM
<b></b>*** M204.2076: <i>n</i> CHECKPOINTS CURRENTLY IN CHKPOINT STREAM
<b></b>*** M204.2077: <i>n</i> USERS CURRENTLY INHIBITING CHECKPOINTS 
<b></b>*** M204.2692: <i>n</i> IS HIGHEST NUMBER OF CHKP RECORDS</p>
<p>
A <code>MONITOR CHECKPOINT USERLIST</code> command displays a basic user line for every user that currently inhibits checkpoints. The following type of transaction information is displayed, where the basic <var>MONITOR</var> display is given for only those users currently inhibiting checkpoints: </p>

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

====Monitoring sub-transaction checkpoints====
<p>
A <code>MONITOR SUBTRAN</code> command displays the sub-transaction checkpoints followed by transaction checkpoint information, similar to the following:</p>

<p class="code">SUB-TRANSACTION CHECKPOINTING STATUS:
DDNAME   SUBTU DRTYF   RECS RECHWM DRTYBU DRTYFT  CDRPGS CDCPGS BLOGPGS  BLOGFT
&#45;-----   ----- ----- ------ ------ ------ ------  ------ ------ -------  ------
CHKPOINT     0     0      0      0      0      0       0      0       0       0
CHKPNTS      0     0      0      0      0      0       0      0       0       0
<b></b>***  M204.2697: START OF SUB-TRANS CHKP AT:  00.000 00:00:00.00,  CHKPOINT
<b></b>***  M204.2698: END   OF SUB-TRANS CHKP AT:  00.000 00:00:00.00,  CHKPOINT
<b></b>***  M204.2697: START OF SUB-TRANS CHKP AT:  00.000 00:00:00.00, CHKPNTS
<b></b>***  M204.2698: END   OF SUB-TRANS CHKP AT:  00.000 00:00:00.00, CHKPNTS
<b></b>***  M204.2073: LATEST SUCCESSFUL CHECKPOINT COMPLETED AT:  05.004  00:46:22.79
<b></b>***  M204.2074: 0 CHECKPOINTS HAVE SINCE TIMED OUT
<b></b>***  M204.2075: 1 RECORDS CURRENTLY IN CHKPOINT STREAM
<b></b>***  M204.2692: 1007 IS MAXIMUM NUMBER OF CHKPOINT RECORDS
</p>
<p>
Where:</p>
<p>
<code>*DDNAME</code> specifies the DDname associated with stream, <code>CHKPOINT</code> or <code>CHKPNTS</code>, (<tt>*</tt> indicates the active DDname) and:</p>
<table>
   
<tr class="head"> <th><p>Count</p></th> 
<th><p> Specifies number of...</p></th> </tr>
   
<tr> <th><var><p>SUBTU </p></var></th> 
<td><p>Sub-transaction updaters</p></td> </tr>
 
<tr> <th><var><p>DRTYF </p></var></th> 
<td><p>Dirty files participating in sub-trans checkpoints </p></td> </tr>
 
<tr> <th><var><p>RECS </p></var></th> 
<td><p>6184-byte records in ddname</p></td> </tr>
 
<tr> <th><var><p>RECHWM </p></var></th> 
<td><p>6184-byte records written to the stream: the high-water mark</p></td> </tr>
 
<tr> <th><var><p>DRTYBU </p></var></th> 
<td><p>Dirty buffers flushed (written) back to files</p></td> </tr>
 
<tr> <th><var><p>DRTYFT </p></var></th> 
<td><p>Milliseconds of elapsed time required to flush the buffers </p></td> </tr>
 
<tr> <th><var><p>CDRPGS </p></var></th> 
<td><p>Real (in-memory) constraints database pages written</p></td> </tr>
 
<tr> <th><var><p>CDCPGS </p></var></th> 
<td><p>CCATEMP - constraints database pages written </p></td> </tr>
 
<tr> <th><var><p>BLOGPGS </p></var></th> 
<td><p>Back out log pages copied </p></td> </tr>
 
<tr> <th><var><p>BLOGFT </p></var></th> 
<td><p>Milliseconds of elapsed time required to copy back out log pages </p></td> </tr>   
</table>

<p>
The <code>MONITOR SUBTRAN</code> command can be expanded to the following forms to provide the previous display plus information on all users inhibiting transaction checkpoints: </p>
<p class="code">MONITOR SUBTRAN USERLIST 
MONITOR SUBTRAN USERLIST SL 
MONITOR SUBTRAN USERLIST SL SERV
</p>
<p>
For more information about the contents of the basic <var>MONITOR</var> display and transaction and sub-transaction checkpoints, see [[Controlling system operations (CCAIN)#ONLINE monitoring|ONLINE monitoring]] and [[Checkpoints: Storing before-images of changed pages]]. </p>

[[Category: System administrator commands]]
[[Category:Commands]]