When the update load on the database is so high that the buffer flush becomes the bottleneck, you can improve performance by reducing the duration of buffer flushes.
Instead of starting one I/O per volume, a buffer flush can initially start a predetermined number of I/Os on each volume and then starts a new one once another I/O on the same volume finishes. This occurs independently on each volume.
This document covers the following topics:
The meaning of the FMXIO parameter has changed
for the new buffer flush method. See the Adabas Operations
documentation.
When ASYTVS=YES (buffer flushes occur by volume),
FMXIO now specifies the number of I/Os to be started in
parallel on each volume. The minimum and default number is 1; the
maximum number is 16. If you specify a number greater than 16, it is reduced to
16 without returning a message.
When ASYTVS=NO (buffer flushes occur in ascending
RABN sequence without regard to the distribution of the blocks over volumes),
the minimum, default, and maximum values continue to be 1, 60, and 100,
respectively.
The setting of FMXIO can be modified dynamically
using the FMXIO=nn command from the operator console or the Modify Parameter
function of Adabas Online System.
