February 4, 2017

Oracle RAC Interview Questions/FAQs Part3

41. What is HAS (High Availability Service) and the commands?
Ans:
HAS includes ASM & database instance and listeners.
crsctl check has
crsctl config has
crsctl disable has
crsctl enable has
crsctl query has releaseversion
crsctl query has softwareversion
crsctl start has
crsctl stop has [-f]

42. How many nodes are supported in a RAC Database?

Ans:
10g Release 2, support 100 nodes in a cluster using Oracle Clusterware, and 100 instances in a RAC database.

43. What is fencing?

Ans:
I/O fencing prevents updates by failed instances, and detecting failure and preventing split brain in cluster. When a cluster node fails, the failed node needs to be fenced off from all the shared disk devices or diskgroups. This methodology is called I/O Fencing, sometimes called Disk Fencing or failure fencing.

44. Why Clusterware installed in root (why not oracle)?


45. What are the wait events in RAC?

Ans:
http://satya-racdba.blogspot.com/2012/10/wait-events-in-oracle-rac-wait-events.html

gc buffer busy
gc buffer busy acquire
gc current request 
gc cr request
gc cr failure 
gc current block lost
gc cr block lost
gc current block corrupt
gc cr block corrupt
gc current block busy
gc cr block busy
gc current block congested
gc cr block congested.
gc current block 2-way
gc cr block 2-way
gc current block 3-way
gc cr block 3-way
(gc current/cr block n-way, n is number of nodes)
gc current grant 2-way
gc cr grant 2-way
gc current grant busy
gc current grant congested
gc cr grant congested
gc cr multi block read
gc current multi block request
gc cr multi block request
gc cr block build time
gc current block flush time
gc cr block flush time
gc current block send time
gc cr block send time
gc current block pin time
gc domain validation 
gc current retry
ges inquiry response
gcs log flush sync

46. What is the difference between cr block and cur (current) block?


47. What are the initialization parameters that must have same value for every instance in an Oracle RAC database?

Ans:
http://satya-racdba.blogspot.com/2012/09/init-parameters-in-oracle-rac.html

ACTIVE_INSTANCE_COUNT
ARCHIVE_LAG_TARGET
COMPATIBLE
CLUSTER_DATABASE
CLUSTER_DATABASE_INSTANCE
CONTROL_FILES
DB_BLOCK_SIZE
DB_DOMAIN
DB_FILES
DB_NAME
DB_RECOVERY_FILE_DEST
DB_RECOVERY_FILE_DEST_SIZE
DB_UNIQUE_NAME
INSTANCE_TYPE
PARALLEL_MAX_SERVERS
REMOTE_LOGIN_PASSWORD_FILE
UNDO_MANAGEMENT

47. What are the new features in Oracle RAC 12c?

Ans:
http://satya-racdba.blogspot.com/2012/10/new-features-in-oracle-rac-12c.html

48. How is the Cluster Health Monitor different from OSWatcher?