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Checking Whether a Transaction Log Is Too Small  



If transaction performance has deteriorated on a node, check whether its transaction log is too small.

Monitoring Transaction Performance describes how to find out whether transaction performance has deteriorated.

How to Perform This Task

  1. Log in to the node that the transaction log belongs to.

  2. Check how many times the transaction log has stalled, using LMCP's SHOW LOG/CURRENT command:
    $ RUN SYS$SYSTEM:LMCP
LMCP> SHOW LOG/CURRENT
    Note the number of checkpoints and stalls displayed by this command.

  3. Wait for five minutes, then repeat the SHOW LOG/CURRENT command. Note the number of checkpoints and stalls again.

  4. Compare the information from the SHOW LOG/CURRENT commands:

    If the number of checkpoints has not changed, wait until the system is busier, then try this task again.

    If the number of checkpoints has increased, and the number of stalls has increased by more than one, the transaction log is too small.

  5. If the transaction log is too small, increase its size. For information about how to change the size of a transaction log, see Changing the Size of a Transaction Log.

Example

This example shows how to check whether node BLUE's transaction log is too small.

Log in to node BLUE. Then check how many times the transaction log has stalled: 

$ RUN SYS$SYSTEM:LMCP
LMCP> SHOW LOG/CURRENT

Checkpoint starts/ends            2464/2464
Stall starts/ends                   21/21
Log status: no checkpoint in progress, no stall in progress.
The number of checkpoints is 2464, and the transaction log has stalled 21 times.

Wait for five minutes, then repeat the SHOW LOG/CURRENT command: 

LMCP> SHOW LOG/CURRENT

Checkpoint starts/ends            2514/2514
Stall starts/ends                   28/28
Log status: no checkpoint in progress, no stall in progress.
The number of checkpoints has increased since the previous reading, and the transaction log has now stalled 28 times, an increase of 7. This means that the transaction log is too small.
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