on 01-13-2010 3:30 AM
We have two servers which are DBCI and DIALOG for our R/3 4.70 system.
We found that one of our query need to run over 9 minutes on DBCI server while it only takes 9 seconds on Dialog server.
The two servers are of exactly the same hardware configuration.
Anybody have any clue about this?
thanks,
Does the behaviour reproduce with every try?
I have seen the opposite lately, so in my case the dialog instance was a lot slower, than the DBCI. In our case the cause where thousands of sql statements generated be the transaction. The execution from the dialog instance took slightly longer per single statement, which added up remarkably in total.
In your case i suggest you check the cpu usage during execution and monitor os paging (swapping). Your db server might suffer memory shortage. A typical case would be, if that transaction uses a lot of memory on the SAP instance.
Other causes could be different parameter settings of the instances etc
Cheers Michael
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Just to be sure, may I suggest to use the simple tool I published some time ago in SDN to verify the speed of the two different server? [Simple ABAP Benchmark|http://www.sdn.sap.com/irj/scn/weblogs?blog=/pub/wlg/3024] [original link is broken] [original link is broken] [original link is broken];
In add, I had similar problem because of the table buffer: there was a large table defined as buffered 100% (complete) in the DDIC (SE11) and in one server the table buffer size was small. As a result there was a continuous table swap decreasing so much the performance.
It was solved defining the table as not bufferable.
Sergio
Hi Sergio, I've tested the two servers with your program and the result showed significant speed issue with dbci server. Please see the results as following:
Transaktion: SE38
Prozessor(s): 9000/800
Host: sscr3db
OS: HP-UX
DB: ORACLE
DB-Release: 10.2.0.4.0
SAP-Release: 620
Execution time per Unit: 30 seconds
-
DBCI DIALOG
CPU Power - Primes found: -
3.280 10225
File System - - Written Mbytes: -
100 2020
RDBMS update - Updated records: 6.700 12300
RAM - Table scans: -
4 75
I think the speed of RAM & File system is obviously abnormal. Maybe I should find some tool running in OS to test the system speed.
Edited by: guoqiang zhang on Jan 17, 2010 8:50 AM
Obviously the tool is very simple and measurement are very influenced by the current workload of the machine.
The CPU power should be measured when no other relevant process are running but normally, if you are not close to 100% utilization, it is quite constant.
File system is not so important, it is most related to interface programs reading/writing on sequential files.
RDBMS update is very important and normally it is important also to exclude network problems between DIALOG and DBCI. So your measurement is strange because normally the opposite occur. Probably the issue is well indicated by the last measurement.
RAM Table scan - I fill a large internal ABAP table into memory and then a scan it sequentially. It could be that DBCI RAM or some SAP buffer (ROLL Area,...) is too small and the scanning requires a lot of OS swap decreasing so much the speed.
I would verify OS paging, Oracle SGA size and allocation, ABAP ROLL area parameters and ABAP table buffer, ABAP SQL trace .
If other SAP instances are running in the same DBCI I would suggest to try a test shutting them down.
Sergio
Keep in mind that the database caches the results. So if you execute this the first time on the DBCI all data need to be read into the database cache, this takes those 9 minutes. If you then execute the same statement on the dialog instance, all necessary data is already in the cache so no more I/O necessary and hence it's much faster.
To really compare those two servers you'd need to
- shutdown the system including database
- startup
- execute on DBCI
- again shutdown everything including database
- start everything
- execute on dialog instance
Markus
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Hi,
Check the network configuration between the dialog serverand the DBCI server.
Verify specially the speed and duplex setting of the ethernet interface.
If it is set to "auto" it can create the kind of problem you are experimenting.
Regards,
Olivier
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