Disable Transparent Huge Pages on Linux | TECHRELAM

 SAP HANA:Disable Transparent Huge Pages on Linux.

If you get error in SAP HANA THP error need to disable the THP in Linux kernel settings.

Run following command to disable the usage of transparent huge pages (THP).

"echo never > /sys/kernel/mm/transparent_hugepage/enabled"

Afterwards, you can check the setting by cat this file. If it returns [never], it means now THP is disabled.

"cat /sys/kernel/mm/transparent_hugepage/enabled"

always madvise [never]

 

Note: The above command will stop only creation and usage of the new THP. The THP which were created and used at the moment, when the command was run, would not be disassembled into the regular memory pages. To get rid of the THP used, you need to restart the corresponding process.

To check system-wide THP usage:

"grep AnonHugePages /proc/meminfo"

 
---> If this command returns a non zero size of AnonHugePages, it means some size of THP is still used.

To check which processes are using THP:

grep -e AnonHugePages /proc/*/smaps | awk '{ if($2>4) print $0}' | awk -F "/" '{print $0; system("ps -fp " $3)}'

Please restart the returned processes to release the used THP.

To make this change permanent, you need to integrate this command line within your system boot scripts.
e.g. If you are using file /etc/init.d/boot.local as boot script, add the line "echo never > /sys/kernel/mm/transparent_hugepage/enabled" to this file.

OR

you can add line "transparent_hugepage=never" to the kernel boot line in /boot/grub/grub.conf.
If you do not know which boot script is used by system, please contact the OS vendor.

 

 

How to change HANA Database schema name during SAP installation | TECHRELAM

 

 

 

Unable to change HANA database schema during the SAP Installation.

 

When we performing a SAP HANA DB installation or system copy using SWPM, the Schema input cannot be changed during the Primary Application Server Instance dialog phase on that time you are only given the option to use the schema name SAPABAP1. There is no option to change the Schema

If you want to change the Schema Name follow the below simple steps.

1. Set the desired schema name in file DEFAULT.PFL: dbs/hdb/schema = <SCHEMA NAME>

2. Start the Primary Application Server Instance dialog phase again.

Now Schema will automatically change what we maintain in the DEFAULT.PFL file.

 

How to free up memory in SAP HANA database | TECHRELAM

 

 

SAP HANA free up memory,

SAP HANA Appliance can be used in smarter way to achieve maximum out of it.

Based on one SAP HANA appliance is used for DEV, TRN,SDK ,,etc. Environments, definitely there will be a major issue in this case – How to handle memory as memory is limited in that particular SAP HANA appliance.

In this situation SAP HANA database manages the loading and unloading of tables into and from memory independently. Actually, the main aim of SAP HANA database is to keep all relevant data in memory. But, SAP HANA have option to do manually load and unload individual tables if necessary to free up memory.follow the below steps to unload the individual tables.it can done by SAP HANA Studio.

==>Logon into Tenant database ==> schema => Tables =>Select the table by right click and choose the option “Unload” and later, If required manually "load"the table into memory again.

This are all the options for free up memory SAP HANA DB.

1.Unload – Free up memory by unloading table from memory.
2.Load – Loading the table into memory.
3.Merge – Triggering delta merge operation for a column table.

We can free up memory using Merge operation manually trigger the delta merge operation for a column table manually in SAP HANA Studio. The delta merge operation is related to the memory management concept of the column store, and SAP HANA Database that manages data organized in columns in memory.

Tcode : ST11 Display Trace File

 

SAP Transaction Code ST11 Display Trace file.

SAP Transaction code ST11 is used to display the Error Log file/trace files in the work directory.No need Operating System access to check trace file. check directly from SAP itself .Using this transaction ST11 we can view the trace files for all the work processes that happen at the OS level with start of SAP and operational status of SAP work process. If you want to save a file locally, choose System -> List -> Save -> Local file.

1. Double-click on a file to display the log / trace.

 

SAP Work process trace W9.