Adjust LRU flushing and automatic tuning in HDR server pairs

When a server is configured for HDR, checkpoints triggered by the secondary database server are nonblocking. These types of checkpoints occur infrequently. If a nonblocking checkpoint is triggered by the secondary server, transactions are blocked on the primary server to make sure that the integrity of the secondary server is not compromised. If nonblocking checkpoints triggered by the secondary server occur on your system, you must tune LRU flushing more aggressively on the primary server to reduce transaction blocking.

To increase LRU flushing, reduce the values of lru_min_dirty and lru_max_dirty in the BUFFERPOOL configuration parameter.

Automatic LRU tuning can be turned on or off independently on each HDR node. The setting can be different on each HDR database server. For information about turning off automatic LRU tuning, see Turn automatic LRU tuning on or off.

For more information about LRU tuning, see the HCL Informix® Performance Guide.


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