UNIX for Advanced & Expert Users

what do you record or look for when using these dummy files to test I/O throughput on disk drives. i have no clue and reading from books sure aint helping much.

i know all about the creation and every other thing there is to it but when it comes to actual testing, how do i use them

this is important so quick replies are welcomed

If you can specify the Question properly ... it would be easier to help you getting ur problem solved.

Happy Answer Hunting

Cheers !!
Mehul Doshi

are you looking to test the transfer speed of your hard drives?

i would opt to use iostat and vmstat when watching the traffic going from drive to drive.


what you should be looking for are any bottlenecks does it look like your useing a disk to much? if so try reorginizeing your data layout.

are you pushing to much info thru and causing a memory bottleneck? or a cpu bottleneck?

as far as threshholds go. just watch your system and try to get a base line of what it normally does.

redbook sg24-4989-00 (RS6000 Performance Tools in Focus)
can give you some basics.

i think we are on the same wave length. I was just going through this myself.

i was just reading a book that talks about creating large dummy files to test disk transfers and also what will happen if a disk was to fill up. (pretty senseless i think. why would you want to know what will happen when a disk fills up?? wouldn't it disallow any files from being created or eventually crash??)

and when you say try reorganizing the data layout, what do mean?? i mean, how do you do that?? say for instance, from looking at the output of iostat, i determine that a particular disk is being hit really bad with lots of information. how do i rearrange the data on that drive to distribute the data being sent to it so that particular drive do not get hit to death.

i dont understand this whole drive thing

I guess the best question here is to ask why you need to do this. I read something similar once in Unix Hints and Hacks (I think...). I've never seen a use for this, other than to test that a drive works OK - like a burn-in period, I guess.

What result are you trying to achieve?