logstat Example: Determine Proximity to FORCE-ABORT-LIMIT
To determine how close your installation is to the FORCE-ABORT-LIMIT, use the information from the Current log file header section in the logstat output. Four statistics are relevant: the Abort interval, the Block count, the Begin, and the End.
The number appearing after Abort interval is the number of blocks in the log file that must be filled before the FORCE-ABORT-LIMIT is reached. The Block count refers to the total number of blocks in the log file. Begin refers to the block marking the log file’s Beginning of File (BOF), and End refers to the block marking the log file’s End of File (EOF). The numbers following Begin and End are divided into three groups separated by colons. The middle group is the most relevant. For example, in the sample output below, block 1702 marks the beginning of the log file.
To calculate how close the installation is to the FORCE-ABORT-LIMIT, follow these steps:
1. Calculate the number of blocks in use.
Because the log file is a circular file, the block marking the file’s beginning can have a higher number than the block marking the file’s end. Consequently, there are two ways to determine the number of blocks in use:
a. If the End of File is larger than the Beginning of File, subtract the BOF from the EOF to obtain the number of blocks in use. For example, if the BOF is 778 and the EOF is 1299, the number of blocks in use is:
1299 - 778 = 521
b. If the End of File is smaller than the Beginning of File, subtract the BOF from the block count figure and add the result to the EOF to obtain the number of blocks in use. For example, in the sample output, the Beginning of File is 1702, the Block Count is 2048, and the End of File is 107. The number of blocks in use is:
(2048 - 1702) + 107 = 453
2. Subtract the number of blocks in use from the Abort interval figure to determine how many blocks are available before the FORCE-ABORT-LIMIT is reached.
For example, in the sample output, 453 blocks are in use and the Abort interval is 1536, so the number of blocks still available is:
1536 - 453 = 1083
----Current log file header-----------------------------------
Block size: 4096 Block count: 2048 Partitions: 1 Buffer count: 4
CP interval: 102 Logfull interval: 1945 Abort interval: 1536
Last Transaction Id: 00002D5B2D5BFA03 Last LSN: <760996813,1054245>
Begin: <760996814:1702:2304> CP: <760996814:1873:3592>
End: <760996815:107:20>
Forced LGA,LSN: <760996814,107,20>,<760996813,1054245>
Percentage of log file in use or reserved: 30
Log file blocks reserved by recovery system: 180
Archive Window: <760996814,1991,3508>..<760996815,107,220>
Previous CP: <760996814,1702,2304>
Status: ONLINE,ARCHIVE,CPFLUSH
Active Log(s): LOG_FILE
Last modified date: 08/29/2024