Category Archives: RAC
Major RAC Wait Events
In a RAC environment the buffer cache is global across all instances in the cluster and hence the processing differs.The most common wait events related to this are gc cr request and gc buffer busy GC CR request: the time it takes to retrieve the data from the remote cache Reason: RAC Traffic Using Slow [...]
SRVCTL
srvctl start instance -d db_name -i “inst_name_list” [-o start_options] srvctl stop instance -d name -i “inst_name_list” [-o stop_options] srvctl stop instance -d orcl -i “orcl3,orcl4″ -o immediate srvctl start database -d name [-o start_options] srvctl stop database -d name [-o stop_options] srvctl start database -d orcl -o mount
Oracle clusterware tools
OIFCFG – allocating and deallocating network interfaces OCRCONFIG – Command-line tool for managing Oracle Cluster Registry OCRDUMP – Identify the interconnect being used CVU – Cluster verification utility to get status of CRS resources
OCR
Oracle clusterware manages CRS resources based on the configuration information of CRS resources stored in OCR(Oracle Cluster Registry).
CRS Resource
Oracle clusterware is used to manage high-availability operations in a cluster.Anything that Oracle Clusterware manages is known as a CRS resource.Some examples of CRS resources are database,an instance,a service,a listener,a VIP address,an application process etc.
Components of RAC – Oracle Clusterware
Oracle clusterware is made up of components like voting disk and Oracle Cluster Registry(OCR).
Advantage of using ASM
Having ASM is the Oracle recommended storage option for RAC databases as the ASM maximizes performance by managing the storage configuration across the disks.ASM does this by distributing the database file across all of the available storage within our cluster database environment.
Seperate homes for ASM instance
It is a good practice to have ASM home seperate from the database hom(ORACLE_HOME).This helps in upgrading and patching ASM and the Oracle database software independent of each other.Also,we can deinstall the Oracle database software independent of the ASM instance.
FAN
Fast application Notification as it abbreviates to FAN relates to the events related to instances,services and nodes.This is a notification mechanism that Oracle RAc uses to notify other processes about the configuration and service level information that includes service status changes such as,UP or DOWN events.Applications can respond to FAN events and take immediate action. [...]
How do we verify that RAC instances are running?
Issue the following query from any one node connecting through SQL*PLUS. $connect sys/sys as sysdba SQL>select * from V$ACTIVE_INSTANCES; The query gives the instance number under INST_NUMBER column,host_:instancename under INST_NAME column.
I have attended Ask Tom Live seminar about 11g Rel2 at Tokyo, Japan. Do you believe it I have got an opportunity to take a snap with him. I am very happy to share with you.