The Question is:
We use Robomon which is reporting high split i/o rates and high window turn
rate - what is the significance of these issues and when do they become a
problem - what can be done about them if they are a performance issue
The Answer is :
A split I/O is generally defined as any I/O request that is split
or segmented into multiple requests to the device driver. A "split
I/O" is counted whenever a segmented I/O is performed and a sys$qio
call to the device driver is not.
Counts alone are not necessarily an indication of a problem, metrics
such as response time or throughput are generally far more useful.
If response or throughput is inadequate, then the examination of the
entire application environment -- split I/Os, the level of internal
(dis)organization of the files, excessive disk fragmentation, I/O
bus and disk performance, system memory, etc -- will all be of
interest. Constraints in one area of the system environment can
cause problems in other areas -- such as insufficient available
physical memory resulting in reduced cache effectiveness which
produces higher storage I/O rates.