Document Type | Troubleshooting
Category | Administration
Applicable Product Versions | 6FS06, 6FS07, 7FS01
Document Number | TADTS060
Issue
After increasing the number of CPU cores from 12 to 40 in an AIX environment, the following error occurred during DB startup.
sql Value of parameter '_DB_BLOCK_LRU_LATCHES' is invalid (condition check failed: '_DB_BLOCK_LRU_LATCHES must be between %d and %d') Internal Error with condition 'jmpbuf != NULL'
This occurs when the product of the number of CPU cores and SMT (Simultaneous Multi Threading) threads exceeds 256, causing DB startup to fail due to an automatic parameter calculation error.
Cause
This issue arises because the maximum value of the _DB_BLOCK_LRU_LATCHES parameter [ (CPU Socket * CPU Core) * 4 ] is limited to 1024.
If the product of CPU cores and SMT thread count exceeds 256, DB startup fails with the error message: Value of parameter '_DB_BLOCK_LRU_LATCHES' is invalid.
- DBWR_CNT = ( CPU Socket * CPU Core ) / 4
- _DB_BLOCK_LRU_LATCHES = ( CPU Socket * CPU Core ) * 4
For example, on a server with CPU Socket = 8 and CPU Core = 32, the calculation is as follows.
- DBWR_CNT = (8 * 32) / 4 = 64
- _DB_BLOCK_LRU_LATCHES = (8 * 40) * 4 = 1024
When the product of CPU Socket and CPU Core exceeds 256, the automatic calculation result for _DB_BLOCK_LRU_LATCHES exceeds the maximum value, causing the problem.
Solutions
1. Apply Patch
You can fundamentally resolve this issue by applying patch 273632d, which removes the maximum value limit of the _DB_BLOCK_LRU_LATCHES parameter.
2. Workaround
For servers where the product of CPU Socket and CPU Core exceeds 256, manually set the following parameters before starting the DB.
- _DB_BLOCK_LRU_LATCHES=1024
- DBWR_CNT=64
Note