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I/O performance on HP-9000 D390 machine

Nandan gogate
Occasional Contributor

I/O performance on HP-9000 D390 machine


I am in the process of comparing I/O performance on sun ultra sparc and HP.
I found that Hp-9000, D390's I/O performance is around 40 % inferior to the I/O performance on ultra-2 using solaris 2.5.

processor speed (which i dont think matters) is almost the same. I am measuring the performance using the following simple program.


#define error
printf("Error , errno: %dn",errno);
return 1;

char buf[8192];
int i=0;
for (i=0; i< 8000; i++)
FILE *fp = fopen("/export/p2/dali/wrF", "w");
if(!fp) error;
for (i=0; i < 3000; i++)
fprintf(fp, "%s",buf);

Then i use timex cmd to find the time required. I make sure the executable is not on the nfs partition. The directory where i create the file (/export/p2/dali/wrF) is on a local partition. I make sure I delete the file before I run the program.

My questions are

1) Is this an acceptable way of measuring an approximate I/O performance ?

2) Has anybody seen such an inferior performance on HP machine compared to Sun machines ?

Any information in this regard is highly appreciated.

Carol Garrett
Trusted Contributor

Re: I/O performance on HP-9000 D390 machine

What speed are the disks on your Sun and HP ?
This may explain the difference. Test their speeds using time dd if=/dev/rdsk/... of=/dev/null bs=1024k count=50 (for 50Mb)

Lets see if the disks are of similar performance.
Alexander M. Ermes
Honored Contributor

Re: I/O performance on HP-9000 D390 machine

This may partially result from the bus topology difference between HP and SUN.
If you connected the SCSI interfaces to the
HP-PB bus, that already makes a lot of a difference. If you have done so, try to get interfaces for the HSC bus.
Alexander M. Ermes
.. and all these memories are going to vanish like tears in the rain! final words from Rutger Hauer in "Blade Runner"
Dan Hetzel
Honored Contributor

Re: I/O performance on HP-9000 D390 machine


It's difficult to say if you're not comparing apples with oranges...

Are the 2 disks (HP/SUN) of the same type and same capacity ? Comparing a 9Gb disk with a 36Gb one will always give speed measurements in favor of the large capacity disk.

As Carol suggested you, you should use dd and let the Operating System do the 'fsync' for you.

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