[buffers]
lazy_threshold=system dependent value
This numeric value is used to together with lazy_delay to set an initial time-out before the database manager begins to flush its cache. The value represents the number of cache buffers considered to liable to be written out in the near future.
When the value is low only the weakest few buffers (i.e. those close to being lost) will initially be candidates for lazy writing, and the database manager will wait longer before writing out most buffers. When the value is high many more buffers will be candidates for lazy writing. If the value is too low lazy writing will be reduced in effectiveness. If it is too high the disk may be "thrashed" as the database manager attempts to write out information too quickly (especially if lazy_delay is set to a very small number). The default value is chosen so that lazy writing only starts after a second or so of inactivity (assuming lazy_delay is not changed).
This value is not used in release 4.622, which uses a completely different algorithm for deciding when to submit writes to the operating system.