Using RAC RDS on Exadata for SAP DBs

[former_member659357]

Hello,

We have Exadata (Oracle engineered system) with production SAP DBs running on it.

Production SAP DBs works in RAC configuration.

DB Oracle Home version: 12.1.0.2.190716

Recently I executed exachk and received one critical issue for SAP Oracle Home:

"Oracle database(s) should be using RDS protocol for inter process communication"

Result for one SAP Oracle HOME:

Status on exadata_adm04:/oracle/HJQ/121:
CRITICAL => Oracle database(s) should be using RDS protocol for inter process communication

DATA FROM exadata_adm04 - /oracle/HJQ/121 DATABASE_HOME - Verify RDS Protocol over is used for interprocess communication [Database Home] 
udp

Recommendation:

Benefit / Impact:

The RDS protocol provides superior performance because it avoids additional memory buffering operations when moving data from process memory to the network interface for IO operations. This includes both IO operations between the Oracle instance and the storage servers, as well as instance to instance block transfers via Cache Fusion.

There is minimal impact to verify that the RDS protocol is in use. Implementing the RDS protocol over InfiniBand requires an outage to relink the Oracle software.

Risk:

If the RDS protocol is not used, IO operations will be sub-optimal.


Action / Repair:

To validate an ORACLE_HOME:
As the owner userid of the ORACLE_HOME, set the ORACLE_HOME and LD_LIBRARY_PATH variables properly and execute the following command:

$ORACLE_HOME/bin/skgxpinfo

The output should be:

rds

To validate a CRS_HOME:
As the owner userid of the CRS_HOME, set the CRS_HOME and LD_LIBRARY_PATH variables properly and execute the following command:

$CRS_HOME/bin/skgxpinfo

The output should be:

rds

If the RDS protocol over InfiniBand is not being used, the appropriate binaries must be relinked.

    NOTE: In all cases, do not use the "relink all" command due to various issues. Use the make commands provided. 

To relink an ORACLE_HOME:
As the owner userid of the ORACLE_HOME execute the following steps with all necessary variables properly set:

    Shutdown any processes using the ORACLE_HOME
    "cd $ORACLE_HOME/rdbms/lib"
    "make -f ins_rdbms.mk ipc_rds ioracle"
    Restart any processes using the ORACLE_HOME 

In alert.log of SAP DBs I see next:

cluster interconnect IPC version: Oracle UDP/IP (generic)

The main question is:

Should we relink an ORACLE_HOME to use RDS for SAP DBs ?

This Oracle Home is deployed by another DBA team that already not works in our organization, so I don`t know either this setting was done by the previous DBA team or this setting comes from the Oracle Home installation.