PHYSBUFF configuration parameter

Use the PHYSBUFF configuration parameter to specify the size in kilobytes of the two physical-log buffers in shared memory.

onconfig.std value
PHYSBUFF 128
units
Kilobytes
values
An integer in the range of 4 - (32767 * pagesize / 1024), where pagesize is the default system page size. The value must be evenly divisible by the default system page size. If the value is not evenly divisible by the page size, the database server rounds down the size to the nearest value that is evenly divisible by the page size.
takes effect
After you edit your onconfig file and restart the database server.

Usage

Double buffering permits user threads to write to the active physical-log buffer while the other buffer is being flushed to the physical log on disk. A write to the physical-log buffer is exactly one page in length. The value of the PHYSBUFF parameter determines how frequently the database server needs to flush the physical-log buffer to the physical-log file.

If the RTO_SERVER_RESTART configuration parameter is enabled, use the 512 kilobyte default value for PHYSBUFF. If the value of the PHYSBUFF configuration parameter is less than 512 kilobytes when the RTO_SERVER_RESTART configuration parameter is enabled, a warning message displays when you restart the server.

The user-data portion of a smart large object does not pass through the physical-log buffers.


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