RE: Scsi I/O speed

Kev,

Make sure that the SCSI CD-ROM or Tape Drive aren't connected to this controller.

Ed

-----Original Message-----
Sent: Wednesday, July 11, 2001 2:56 PM
To: Multiple recipients of list ORACLE-L

Well yeah, all of this makes perfect sense to me. However, if I am testing the devices I would assume that the test software is going to send as much info as it can down the pipe, you know stuff it. With the Ultra/160 I am assuming that there is only a 80mb/s drive in there, I never opened it up and looked, but I will now. I will use a couple different utilities and see if the rates are the same.

        Also, I know that the drives I have in these machines are all 80mb/s drives, at least in the other machines, so there shouldn't be any device that is "bringing" down the rate. I don't know, but I would love to try and iprove this rate.
KK

-----Original Message-----
Sent: Wednesday, July 11, 2001 2:00 PM
To: Multiple recipients of list ORACLE-L

Kevin,

One thing to remember with SCSI...it's not necessarily the speed of the controller that matters. The SCSI bus will be slowed down to the speed of the slowest device in the chain...or on the bus. For example, if you have a controller with 80mb/s and 3 HDs with 80mb/s and 1 HD at 40mb/s...all running off the same controller...the bus speed will be no more than 40mb/s
(the speed of the slowest device). Again, that is the theoretical max
speed.

Ed

-----Original Message-----
Sent: Wednesday, July 11, 2001 12:22 PM
To: Multiple recipients of list ORACLE-L

Hi all,

        I was measuring the i/o performance of my scsi drives and I have a quick
question that maybe someone could shed some light upon. Currently I am using Ultra 2/Wide scsi conrollers, this is supposed to have an I/O of 80mb/s. Well, when I perform the test all of the machines seem to be operation at halp of the max speed. One operates at about 20mb/s read and write and the others are even slower than that. Now on the first one, it is the only HD on the controller, on the others there are two disks. Even on my Ultra/160 it seems to be maxing out at 40 read and write.

        Am I missing something? Am I reading this the wrong way? Help:(

Sincerely,
Kevin Kostyszyn
DBA
Dulcian, Inc
www.dulcian.com
kevin_at_dulcian.com

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