100% Disk Utilization

[Former Member]

Hi All,

Most of the time of of our application server is showing 100% disk utilization and due to this system performance is badly affected. Actually Apps server is having only one disk c drive and OS as well as SAP Application sits on the same disk. other apps servers are also having the same configuration of one disk.For all apps server we are using Windows NT and CI is on HPUX platform. How to resolve this issue?

Pls help

Regards,

Prashant

[former_member251078 · Accepted solution]

Hello Prashant,

Have you checked Top CPU tab in ST06 --> Detailed analysis screen?? Could you please get the same information. I believe there could you also verify, was there any third party tools like antivirus scanner were running at that time in that application server , when the performance was bad.

As you mentioned you noticed this performance degradation in only one apps server. So check that network through put at

that time.

Hope this helps

Yours Sincerely

Dileep

[Former Member · Accepted solution]

Hi Dileep,

Last weekend we restarted all apps servers after that all apps servers are bahaving fine ,including the system which was showing high disk utilization is also performing well, actually there were lot of red marked swaps in the server before the restart ,is this the reason for the bad performance and high disk utilization?

Regards,

Prashant

[Former Member]

Hi Prashant,

Kindly provide the follwoing details :

1. Time slot when disk utilization is 100%

2. Simultaneously check which jobs are affecting the performace.

Regards,

Rahul.

[Former Member]

Thanks

[Former Member]

Hi

Swap is always a problem in a SAP system, as you're using disk as memory instead of physical memory ( thousand times slower ).

I understand that if you've got several application servers, users get into the system by logon group ( smlg ) and not directly to application servers. If this is not the case, first of all you should configure the logon group.

By other side, and taking into account the memory parameters you explained, when I had this problem in an application server, it used to be a parameters mistake in server's profile. Check the profile of this server against the other servers, specially buffer sizes.

And finally, my oppinion is that Windows isn't the best solution for application servers. I use Suse 9 in my servers and never got this kind of problems. I'm a bit disconnected about windows platforms, but some time ago, you had to restart windows servers periodically ( weekly or monthly ) to cleanup resources. Windows hasn't the best memory management solution.

Well, hope this helped

Regards

[Former Member]

Hi Xisco,

Could you pls let me know what all are the parameters in server profile that I need to check and how to make sure that values setted are correct or not.

Regards,

Prashant

[Former Member]

Hi Prashant,

The High Disk Utilisation indicate quite a few things lets discuss one by one.

1. Here i could suspect the DB time may be high and i think there would be presence of expensive sql statements, so just check in st04.

2. If you have Oracle Database then there is a chance of I/O bottleneck.

In the oracle session the I/O section is broken into subsections as

follow:

High Average Response Time per Read Request

High Average Response Time per Commit

High Average Response Time per Buffer Busy Wait

High Number of Waits for Free Buffers

High Number of Waits for Buffers being written to Disk

High Number of Space Waits for the Log Buffer

File System Response Times

So check the above mentioned part providers.

3. In the operating system monitor of the database server also we can find

the high numbers of I/O wait. This value indicates problems in I/O. So check on this.

4. And at last do monitor SM66 and if possible trace through st05 then we can

narrow down the problem why its going for Disk utilisation regularly. Try to find out the Report Name as well.

Finally analys the subsystem using external tools and still the problem is not getting solved the get in conatct with thehardware vendor of th I/O sub system.

Thank you,

Tilak

[Former Member]

Hi Tilak ,

My concern is we are having 3 other dialog instances but why we are facing disk utilization on this particular server only? CI is running fine.......ne guess?

Regards,

Prashant

[Former Member]

Hi Prashant,

I found one SAP Note 1009297 Windows Server 2003 Family: High Paging Rate

Which details the reason for this high disk usage and a fix that is provided by Mircosoft.

Please update me on your progress.

Thank you,

Tilak

[Former Member]

Hi Tilak,

pls keep an eye on this thead I will update u soon

Regards,

Prashant

[Former Member]

Hi Tilak,

Thanks a lot for ur help, Last time when disk utilization was 100% system was very slow(only this particular dialog instance) when I checked the memory out of 16 GB of RAM 13 GB was free and CPU Idle % was 98 . Do you think this not will solve the problem?also when i checked through OS utility "perfmon" processing % was very less as well as pages/sec were also fine. As soon as disk utilization decreases system starts behaving fine. Please suggest. Do we need to contact microsoft for this?

Regards,

Prashant