[buffers]
tracksize=128
This value represents the number of adjacent 512 byte disk sectors that DP4 will attempt to read and write simultaneously by coalescing pages.
Disk controllers usually have an optimum data transfer size, for which reading or writing the disk reaches a peak transfer rate. Usually this is somewhere around 64K bytes (acutally the peak may differ for read and write operations, but DP4 does not yet cater for this).
In release 4.622 DP4 may attempt to re-order disk reads and writes to enable it to access the disk using amounts of data larger than a single page of disk buffers. For example if the database manager needs to read two index nodes that are close together DP4 may allocate extra pages to allow the two index nodes to be accessed in a single operation. Most changes of this type only take place if the bypass_cache=2 setting is enabled.