disk io

[j773303]

If the disk IO always running high percentage around 60-70% due to the application. Are there any kernel parameters to tune it for more efficient for Disk IO? Thanks.

[Leif Halvarsson_2 · Accepted solution]

Hi,
I don't know if there is any kernel parameter which affect I/O performance but you can sometimes get improvments (depending on the application) by changing filesystem parameters (blocksize etc.). But, the best solution is a faster disk.

[David Burgess]

If you are running a database then make sure you have data and indexes on different disks. That will help. Otherwise look to have more controllers and less disks per controller.

HTH

Regards,

Dave.

[G. Vrijhoeven]

Hi,

If possible, use more disks ( striping ). If you need help on that come back to us.

Gideon

[Jeff Schussele]

Hi,

Yes - take a look at three things that can really help.

1) Multipathing - either HW (alternate links) os SW (Powerpath or AutoPath)
2) Mount Options
3) Efficient use of buffer cache

And as noted - spreading the load across disks/LUNs should be your first priority.

My 2 cents,
Jeff

[I.Delic]

Beste,

Firste you have to find reason why do disks works hard. Maybe you have memory problem ?
Swapping ?
Check vmstat 1 10. Values van PI AND PO ( pagein and pageout ) should be nearly 0, otherwise you have big swap problem.
IF you have this problem it is logical that you have an high IO on you disk.

Maybe this help

Idriz

[José Enrique González]

Take a look to /var/adm/syslog/syslog.log to see if you're having 'SCSI reset' or any other hardware problem related to that disk. Usually, high disk contention is associated to hardware failures. Hope it helps

[Bill Hassell]

The kernel is always running as fast as it can so there is no magic kernel parameter to go faster. Disk I/O is caused by applications so the first (and usually most effective) check is to look at the apps that are causing the disk activity. There is nothing wrong with 100% disk I/O unless the expected response times for the apps are below expectation.

If changing the apps is not an option, then you have to spread the I/O across more disk channels. This involves identifying which disks are the busiest, then finding the files and directories that are being accessed and finally, moving these files and directories to other disks and restarting the applications.

[RolandH]

Some questions.

- How have you measured this value?
- What's wrong with this value (What did you expect)?
- What OS are you using? 11.0 11.11 or 11.23
- How are disks for your application attached to your system?

Do you want less then 60-70% or do you want more than this?
If I interpret this value as I think you do I am happy to have it always near to 100%. Because this shows me that I get the performance I have paid for.

Roland