THERE ARE 4 types of table type buffering are:
1. No Buffering.
2. Full Buffering.
3. Single record Buffering 4. Generic Buffering.
1. No Buffering:
The table Which are relatively large and frequently updated is not eligible for buffering . Ex: Mara, V bank, EKPO, BSEG.
2. Full Buffering:
The table which are relatively small are rarely updated is eligible for full buffering.
Ex: T000, TBDLS.
3. Single Record Buffering:
The tables which are considerably small are buffered by using their key.
Eg: USR02
4. Generic Buffering:
The buffering is performed based on group of fields.
Ex: T001 (Company Codes) Buffering For Tables:
When the table is defined SAP categories whether table can be buffered or not it provides various options:
1. Buffering not allowed.
2. Buffering allowed.
3. Buffering allowed but switched off (Customer can only change this.)Especially when we are working on development system buffering is not required.
BUFFER SYNCHRONISATION:
When more than one instance is configured we need to set the buffer synchronization option if not users get the invalid data as response or the request cannot make use of buffers.
BUFFER WORK FLOW:
1. User goes to the database and fetches content into the R/3 buffers in various instances.
2. User on one of the instance modifies the data but the same data is available to users on the other instance.
3. Now the modified content be synchronized with other instance needs to inform the user that content is updated and advised to invalidate the buffer content.
4. When the data is fetched into buffers it logs into the table DD log
5. When from the user is fetching the content from the buffer it will check the time stamp record. There is a difference in the time stamp user gets data from database. On the other hand there is a parameter RDISP/BUFF REF TIME is 60sec to 3hours.
6.Inorder to set the parameter we need to activate buffering by using parameter RDISP/BUFF REF MODE set to send on, execute if we do not want the buffer synchronization send off, exe off.
It is possible to allow 5000 to 1000 per day 50 do not panic when you see swaps in
‘ST02’.
Buffers are displayed.
Buffer: B.H.R | allocated | free | free % | allocated | free | free | swaps 94%
In this swaps need to be monitored.
SE13: Technical settings of tables
Buffering allowed / not allowed/ allowed but switched off no buffering / 100% / all buffering / single / generic
Note:- On a central instance configure rdisp/ buffer mode as send off No buffering / 100%/all buffering/single/generic
Note;- On a central instance configure rdisp / buffer mode as send off, exe off configure to send on exe auto if more than one instance is complicated.
Setting the parameter to off we will dramatically increase the performance.
Tracing:- [ST01 system trace] or [ST05 SQL trace] It is used to trace the following ST01: 1. Authorization Trace:- It is used to trace missing authorization [it will be default in security]
2. Kernel Trace:- It is used to identify the functionality of kernel when it is being executed. It will specifies if any executable is out dated and based on that we may need to update them.
ST05:- 1 SQL Trace: - It is used to identify the expensive SQL statements with estimated cost.
Go to ST05 and activate the trace for the logged in user.
We can also activate the trace with filter to specify user and program / transaction name.
ABAP development team can write the SQL statement to fine the SQL execution plan.
2 Enqueu Trace:- It is used to find the causes of expensive Enqueu time.
3 RFC Trace:- It is used to fine the causes of RFC+CPI time buffer trace is used when more swaps are recorded.
4 Buffer Trace
ST01:- It is used friendly to work with all traces and with all combinations.
ST06:- It is used to identify the utilization of CPU and memory resources.
Go to ST06 and ensure that CPU idle time should not be less than 30%
If it goes down below 30% click on detail analysis men and select to CPU. To identify the top CPU services or users. Count specifies the number of CPU and utilization for 1st, 5th and 15th min is displayed.
Identify the top CPU users and services and fine tune the program used by tem using SE30.
It also displays the physical memory available and free memory along with swap space.
We can also stop and start SAP OS collector from ST06.
Go to detailed analysis men use LAN check by PING to presentation servers and database servers.
ST07:- It is used to identify the no of applications and total, no of users, total no of w/p throughout the system along with the load on the applications with users and processes using that application. It is use to find the load on the applications and determine which application is it mostly used for getting the requirement for log on load balancing and it is also used to determine the buffers used, the response time of the system and DB memory and DB access.
ST11:- It is used to display the log files from E: usr/SAP/SID/DEVBMGS/work CCMS
[Computing Center Monitoring System]
It is used to monitor the system based on alerts threshold values. It is also called as alert monitor it is a single window where the complete system can be monitored and alerted for change management.
We can use SAP predefine monitors or we can create and adapt our own monitors.
Go to RZ20 Extras
Activate maintenance function on create or copy the monitor from the standard template.
RZ20 consists of monitor sets, monitors, and monitor tree elements [MTE]
MTE are assigned with properties and methods
Go to RZ21 to define and assign properties and methods
How the information is passed to RZ20? The methods run the various jobs periodically and update CCMS.
The method can get the information from transaction, report or using a functional module.
Properties are defined to collect the information based on time interval and change the traffic light from
White – yellow – red – green
The threshold values are defined to change the above colors based on output.
Let us say the system should check DB02 and report missing indexes.
The background job monitors DB02 and if there are any missing indexes it displays in red color, similarly, backup fails, background job fails, update fails, and lock mechanism failure etc are monitored and displayed through CCMS.
It is an alert monitor to display the errors on windows. This reduces the task of check list, but there should be someone to monitor this CCMS.
MTE properties to specify traffic lights based on the output from methods.
Methods are assigned with reports, transactions, and Function modules to run in the background in non dialog mode and get the information into CCMS.