Dumping the contents of the log using the dmpmqlog command
Use the dmpmqlog command to dump the contents of the queue manager
log. By default all active log records are dumped, that is, the command starts
dumping from the head of the log (usually the start of the last completed
checkpoint).
The log can usually be dumped only when the queue manager is not running.
Because the queue manager takes a checkpoint during shutdown, the active portion
of the log usually contains a small number of log records. However, you can
use the dmpmqlog command to dump more log records using one of the
following options to change the start position of the dump:
The
output from the dmpmqlog command is the Log File Header and
a series of formatted log records. The queue manager uses several log records
to record changes to its data.
Some of the information that is formatted is only of use internally. The
following list includes the most useful log records:
- Log File Header
- Each log has a single log file header, which is always the first thing
formatted by the dmpmqlog command. It contains the following fields:
|
logactive |
The number of primary log extents. |
|
loginactive |
The number of secondary log extents. |
|
logsize |
The number of 4 KB pages per extent. |
|
baselsn |
The first LSN in the log extent
containing the head of the log. |
|
nextlsn |
The LSN of the next log record
to be written. |
|
headlsn |
The LSN of the log record at the
head of the log. |
|
tailsn |
The LSN identifying the tail position
of the log. |
|
hflag1 |
Whether the log is CIRCULAR or
LOG RETAIN (linear). |
|
HeadExtentID |
The log extent containing the
head of the log. |
- Log Record Header
- Each log record within the log has a fixed header containing the following
information:
|
LSN |
The log sequence number. |
|
LogRecdType |
The type of the log record. |
|
XTranid |
The transaction identifier associated
with this log record (if any).
A TranType of MQI indicates
a WebSphere MQ-only transaction. A TranType of XA is involved
with other resource managers. Updates involved within the same unit of work
have the same XTranid. |
|
QueueName |
The queue associated with this
log record (if any). |
|
Qid |
The unique internal identifier
for the queue. |
|
PrevLSN |
The LSN of the previous log record
within the same transaction (if any). |
- Start Queue Manager
- This logs that the queue manager has started.
|
StartDate |
The date that the queue manager
started. |
|
StartTime |
The time that the queue manager
started. |
- Stop Queue Manager
- This logs that the queue manager has stopped.
|
StopDate |
The date that the queue manager
stopped. |
|
StopTime |
The time that the queue manager
stopped. |
|
ForceFlag |
The type of shutdown used. |
- Start Checkpoint
- This denotes the start of a queue manager checkpoint.
- End Checkpoint
- This denotes the end of a queue manager checkpoint.
|
ChkPtLSN |
The LSN of the log record that started this checkpoint. |
- Put Message
- This logs a persistent message put to a queue. If the message was put
under syncpoint, the log record header contains a non-null XTranid. The remainder of the record contains:
|
SpcIndex |
An identifier for the message
on the queue. It can be used to match the corresponding MQGET that
was used to get this message from the queue. In this case a subsequent Get Message log record can be found containing the same QueueName and SpcIndex. At this point the SpcIndex identifier
can be reused for a subsequent put message to that queue. |
|
Data |
Contained in the hex dump for
this log record is various internal data followed by the Message Descriptor
(eyecatcher MD) and the message data itself. |
- Put Part
- Persistent messages that are too large for a single log record are logged
as a single Put Message record followed by multiple Put Part log records.
|
Data |
Continues the message data where the previous log record
left off. |
- Get Message
- Only gets of persistent messages are logged. If the message was got
under syncpoint, the log record header contains a non-null XTranid. The remainder of the record contains:
|
SpcIndex |
Identifies the message that was
retrieved from the queue. The most recent Put Message log
record containing the same QueueName and SpcIndex identifies the message that was retrieved. |
|
QPriority |
The priority of the message retrieved
from the queue. |
- Start Transaction
- Indicates the start of a new transaction. A TranType of MQI indicates
a WebSphere MQ-only transaction. A TranType of XA indicates one that involves other
resource managers. All updates made by this transaction will have the same XTranid.
- Prepare Transaction
- Indicates that the queue manager is prepared to commit the updates associated
with the specified XTranid. This log record is written
as part of a two-phase commit involving other resource managers.
- Commit Transaction
- Indicates that the queue manager has committed all updates made by a
transaction.
- Rollback Transaction
- This denotes the queue manager's intention to roll back a transaction.
- End Transaction
- This denotes the end of a rolled-back transaction.
- Transaction Table
- This record is written during syncpoint. It records the state of each
transaction that has made persistent updates. For each transaction the following
information is recorded:
|
XTranid |
The transaction identifier. |
|
FirstLSN |
The LSN of the first log record
associated with the transaction. |
|
LastLSN |
The LSN of the last log record
associated with the transaction. |
- Transaction Participants
- This log record is written by the XA Transaction Manager component of
the queue manager. It records the external resource managers that are participating
in transactions. For each participant the following is recorded:
|
RMName |
The name of the resource manager. |
|
RMID |
The resource manager identifier.
This is also logged in subsequent Transaction Prepared log
records that record global transactions in which the resource manager is participating. |
|
SwitchFile |
The switch load file for this
resource manager. |
|
XAOpenString |
The XA open string for this resource
manager. |
|
XACloseString |
The XA close string for this resource
manager. |
- Transaction Prepared
- This log record is written by the XA Transaction Manager component of
the queue manager. It indicates that the specified global transaction has
been successfully prepared. Each of the participating resource managers will
be instructed to commit. The RMID of each prepared resource
manager is recorded in the log record. If the queue manager itself is participating
in the transaction a Participant Entry with an RMID of zero will be present.
- Transaction Forget
- This log record is written by the XA Transaction Manager component of
the queue manager. It follows the Transaction Prepared log
record when the commit decision has been delivered to each participant.
- Purge Queue
- This logs the fact that all messages on a queue have been purged, for
example, using the MQSC command CLEAR QUEUE.
- Queue Attributes
- This logs the initialization or change of the attributes of a queue.
- Create Object
- This logs the creation of a WebSphere MQ object.
|
ObjName |
The name of the object that was
created. |
|
UserId |
The user ID performing the creation. |
- Delete Object
- This logs the deletion of a WebSphere MQ object.
|
ObjName |
The name of the object that was deleted. |