RAC and ASM

RAC and ASM

 What is ASM?

 ASM implements mirroring and striping.

What is RAC 9i?

You use redundancy to remove SPOF's - single points of failure.

You use raid for example to make sure the disks never fail.

You use dual NIC's and networks to make sure the network never fails.

RAC allows you to use more then one computer in a cluster to make sure the failure of a single computer (n-1 computers actually) doesn't bring down the database. By running more then one instance of oracle on different computers -- all accessing the SAME database -- we can increase (greatly) the availability of the system .

How is RAC different(or similar) from OPS? What is the difference between RAC and OPS?

I assume you mean OPS -- Oracle Parallel Server.

It is all about the way in which cache fusion works in a write write conflict.

RAC is a new more robust OPS.

Who is the Master Node in my Oracle Cluster?
OCR backup is done by the OCR Master, which can be any node in the cluster. It is therefore recommended to configure the backup location to a shared folder that is accessible from all cluster nodes.
The CRSD (Cluster Registry Service Demon) is the one who deals with the OCR, which is why I search through this log file.The Master Node of the Cluster is the one who will become the only surviving node if the interconnect fails completely. It is also the node who will pass the time to the other nodes in the absence of NTP via CTSSD (Cluster Time Synchronization Service Demon)

ps -ef | grep d\.bin

[OBIT11]-->grep -i 'ocr master' *.*

crsd.l10:2018-03-28 05:46:41.377: [  OCRMAS][2977233216]th_master:12: I AM THE NEW OCR MASTER at incar 1. Node Number 1

[oracle@amxdobi01:/u01/oracle/11.2.0/grid/log/amxdobi01/crsd]

[OBIT11]-->cd /u01/oracle/11.2.0/grid/bin

[oracle@amxdobi01:/u01/oracle/11.2.0/grid/bin]

[OBIT11]-->olsnodes -n

amxdobi01       1

amxdobi02       2

[oracle@amxdobi01:/u01/oracle/11.2.0/grid/bin]

[OBIT11]-->

 OCR and voting disk and How these are being used for CSSD and CSRD process ?

The CRSD (Cluster Registry Service Demon) is the one who deals with the OCR

The CSSD (Cluster Synchronization Service Demon) is the one who deals with the Voting File that is used to determine which nodes must reboot and which nodes will survive in case of a problem with the Interconnect

Another important change regarding the Voting File is that it is no longer supported to take a manual backup of it with dd. Instead, the Voting File gets backed up automatically into the OCR. As a New Feature, you can now do a manual backup of the OCR any time you like, without having to wait until that is done automatically – which is also still done:

 listing voting disk .

 [oracle@amxdobi01:/u01/oracle/11.2.0/grid/bin]

[OBIT11]-->crsctl query css votedisk

##  STATE    File Universal Id                File Name Disk group

--  -----    -----------------                --------- ---------

 1. ONLINE   5c6811d95e20ef01bf3e033e478ce219 (/dev/emcpowerh1) []

 2. ONLINE   811c06b3d5234f95bf504002bcd5180e (/dev/emcpowerh2) []

 3. ONLINE   49bba4c225a55ff3bfd9cacff3759c6a (/dev/emcpowerh3) []

Located 3 voting disk(s).

[oracle@amxdobi01:/u01/oracle/11.2.0/grid/bin]

[oracle@amxdobi01:/u01/oracle/11.2.0/grid/bin]

[OBIT11]-->ocrconfig -showbackup

amxdobi01     2018/05/06 02:11:05     /u01/oracle/11.2.0/grid/cdata/OBID_cluster/backup00.ocr

amxdobi01     2018/05/05 22:10:54     /u01/oracle/11.2.0/grid/cdata/OBID_cluster/backup01.ocr

amxdobi01     2018/05/05 18:10:52     /u01/oracle/11.2.0/grid/cdata/OBID_cluster/backup02.ocr

amxdobi01     2018/05/05 02:10:44     /u01/oracle/11.2.0/grid/cdata/OBID_cluster/day.ocr

amxdobi01     2018/04/25 14:08:33     /u01/oracle/11.2.0/grid/cdata/OBID_cluster/week.ocr