I hope gurus here can help me to clear some confusions regarding 11gR2 RAC environment.
(1) Can I use the same owner (ie oracle) for both the Oracle Grid Infrastructure installation and the Oracle RAC installation ? Like :
GRID_HOME=/oracle/11.2/grid ## Grid Infrastructure binary
ORACLE_HOME=/oracle/11.2/db ## Oracle RAC binary
(2) Whats the difference between CSR_HOME and GRID_HOME ??
(3) If not using ASM in RAC environment, should I still need to create "storage administration role" (i.e. SYSASM/OSASM..) ?
(4) Is password file necessary for RAC instances ?
Answer with detailed explanation is highly appreciated. Thank you in advance.
i) Yes, you can use same owner for both Grid infra and Oracle RAC DB installation. But remember Grid_home and Oracle_home must be different location.
ii) In Oracle 10g, we used to create CRS_HOME which contains the oracle clusterware software components binary files(In Oracle 10g asm comes with database and not with clusterware software)., Then they will create separate home for ASM and databases. But in Oracle 11g they combined both clusterware components and ASM together and installed in a single directory called GRID_HOME. So in Oracle 11g, ASM comes with grid infrastructure software. and Database software comes separate.
iii) If you are not using ASM, There is no need to create SYSASM/OSASM roles. Then you have an one and only option is to use Shared file system in RAC environment. But using Shared file system in RAC environment is of no use at all. So if RAC exist, ASM will be there..
iv) Yes password file is necessary for RAC instances.
For ASM releases prior to 11gR2 password files should either be placed on a shared filesystem (and symlinked from $ORACLE_HOME/dbs) or password file changes should be performed manually on all instances in order to keep the password file contents synchronized on all nodes.
For ASM releases from 11gR2 onwards there is no need to place the password files on a shared filesystem because password file changes are automatically propagated to remote instances.
Thank you for your helpful advice. I have one more question :
Quoting : "But using Shared file system in RAC environment is of no use at all. So if RAC exist, ASM will be there.. "
--> Certified Shared file system on Oracle RAC is supported according to Oracle documents (i.e. NFS file system on a certified NAS filer/Veritas Storage Foundation ..) Would you please explain more to clarify your point ??
Thank you again,
ASM will work directly with block devices and provide a combination of software RAID and volume management specifically built for Oracle files. However, files stored within ASM are not available to the operating system without the use of special tools.
This means that ASM volumes (called ‘diskgroups’) cannot simply be mounted at the OS level and browsed, copied, edited, or otherwise managed. However, a whole host of commands have been created which can be performed through SQL*Plus. Tools such as ASMlib and ASMCMD simplify management of files inside of ASM volumes. For example, ASMCMD allows an ASM volume to be browsed as if it were a standard filesystem: The deployment is little difficult but management is very effective. Disks can be added and removed in notime.
But, Even though the NFS is certified, management is little tedious when compared to ASM.
I would recommend ASM with asmlib drivers rather than NFS from my experience.
Oh okay Rich.
But Anyway there are people who use shared file system for storage. It depends on their usage. But from my experience and all environments what i saw till now is with RAC and ASM together. Cool. If you find it useful, please close this thread as answered and others may get find useful information from our discussion.
Knowledge is power when shared...
Thanks and Regards,