Re: Disk Bottleneck



Herb Martin wrote:
Hey i have been reading the microsoft's windows 2000 resource kit about
detecting disk bottleneck, but i have a hard time understanding it
[quoted text clipped - 17 lines]
Well the average on the PC that im measuring is less than 20 but sometimes
when it gets really busy its average is 50 and going over 100.

Spikes mean nothing -- it's all about sustained paging (and this is true for
most other non-cumulative counters).

For instance, programs "page into" memory -- this is perfectly natural and
leads to a lot of paging when large programs load and initialize or when
they
switch subsystems.

This is also true if you are have to page to task switch -- again perfectly
natural to see paging when a program that has been unused comes back
to the foreground or other active use.

and why not measure page faults?

The "Page Faults" counter includes soft faults (those to/from the Transition
List) which never go to the hard drive and which are serviced by RAM.

where can i see this X Second/Transfer.

Disk counter. Physical disk counter.

also what are the indication of a disk bottleneck?

NOT having a pages per second* problem and having high disk usage
(above 50%, maybe above 90%) and generally accompanied by high
disk QUEUE Length (data transfers waiting on the disk controller for
service).

*Technically it is possible to have high pages per second while not
having a RAM issue but this is VERY UNCOMMON today -- such
can be caused by badly designed applications, apps with working set
configured too small, or similar app problems. Very uncommon.


ok everything is clearing up now :)

also i have checked the counters for memory, processor, disk and network on
the performance monitor and wow its so many... do you really have to
understand all of those in order to fully identify the cause a bottleneck...

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