AIX disk I/O bandwidth 3

[J1gh2]

Hi Guys

We are doing performance testing/tuning and would like to know the disk I/O bandwidth on aix 5.3? These are (DS4800) SAN attached disks. How do I do this?

Regards

 

[khalidaaa]

You can measure the disk throughput doing this:

For Read Throughput:

# time dd if=/fs/1000m of=/dev/null bs=1024k

For Write Throughput:

# sync; date; dd if=/dev/zero of=/fs/1000m bs=1024k count=1000; date; sync; date

(The time between the first and the third date command is the total amount of time it took to write the file to disk)

Regards,
Khalid

 

[RMGBELGIUM]

when you do that write test, you will write from memory to cache, because your disk controller has onboard cache,so I would go for a count of about 6000, thus bypassing the cache
at a certain moment.

rgds,

R.

 

[J1gh2]

Guys

thank you very much

 

[p5wizard]

Depending on how write-intensive your application is (or isn't) and how big the DS4800's cache is, you're probably not really interested in knowing how the controllers/disks inside the DS4800 are coping with writing cache to disk.

Once the data is in the DS4800's cache, the story ends from your pseries server's point of view: the write operation is finished...



HTH,

p5wizard

 

[foobar13]

Have a look at iozone

http://iozone.org/.

It can be used to test the io of disk infrastructure and has a very impressive list of tests and options. It's easy to graph the results using a spreadsheet like Openoffice or Excel and the web site shows some nice examples. I've used it extensively.

 

[J1gh2]

Hi foobar13

This is great. Thanks a lot

 

[shortline]

Has anybody used iozone with large (> 2GB) test sizes?
I got errors with 3.383 with anything over 2 GB.

Thank you