What is I/O?

["Burns, Bryan" <Bryan_Burns@xxxxxxxxxxxx>]

The term I/O is used a lot with respect to performance but I'm not sure what it 
means.  Can someone give me a primer?  What does it mean to the system if a job 
is doing "A LOT OF I/O"?  Doing a lot of reading and writing to disk?  What can 
you do about it?  Would a batch query that's using a lot of CPU be doing a lot 
of I/O too?  That, I could probably control.

What's a lot of I/O on a 9406 520 with 12 disk units?  I started an I-nav 
monitor this morning and one of the I/O high points is 600 operations per 
second.  Is this trivial?   

Thanks,

Bryan Burns
IBM Certified Specialist - iSeries System Command Operations V5R2 
M.I.S. Department
ECHO, Incorporated
www.echo-usa.com