OCM OCM High Availability & Disaster Recovery 1 — Questions and Answers
Question 1: In Oracle Data Guard, which role does the primary database's standby perform when it actively processes redo in real time?
- Snapshot Standby
- Logical Standby
- Physical Standby in Maximum Availability mode (Correct answer)
- Far Sync Instance
Correct answer: Physical Standby in Maximum Availability mode
A Physical Standby in Maximum Availability mode applies redo data in real time using Redo Apply (MRP), maintaining synchronization with near-zero lag.
Question 2: What is the primary purpose of a Far Sync instance in Oracle Data Guard?
- Serve read-only queries to offload reporting from the primary
- Receive redo from the primary synchronously and forward it asynchronously to terminal standbys (Correct answer)
- Act as a witness for Data Guard Fast-Start Failover
- Host an Active Data Guard standby for zero-data-loss protection
Correct answer: Receive redo from the primary synchronously and forward it asynchronously to terminal standbys
A Far Sync instance sits close to the primary, receives redo synchronously (zero data loss), and ships it asynchronously to distant standbys, combining zero-RPO with low latency.
Question 3: Which Oracle RAC component manages cluster membership and arbitrates split-brain scenarios?
- Grid Naming Service (GNS)
- Cluster Synchronization Services (CSS) (Correct answer)
- Oracle Cluster Registry (OCR)
- Virtual IP (VIP)
Correct answer: Cluster Synchronization Services (CSS)
CSS (Cluster Synchronization Services) maintains node membership, detects failures through missed heartbeats, and initiates node eviction to prevent split-brain data corruption.
Question 4: In Oracle RAC, what does Cache Fusion do?
- Merges UNDO segments across all nodes into a single tablespace
- Transfers data blocks between node buffer caches over the private interconnect to avoid disk reads (Correct answer)
- Fuses the redo streams from all instances into a single redo log
- Merges duplicate index entries across RAC instances
Correct answer: Transfers data blocks between node buffer caches over the private interconnect to avoid disk reads
Cache Fusion uses the high-speed private cluster interconnect to ship modified data blocks directly between instance buffer caches, eliminating the need for intermediate disk writes.
Question 5: What is the Recovery Time Objective (RTO) primarily concerned with?
- Maximum acceptable data loss measured in time
- Maximum acceptable duration of downtime after a failure event (Correct answer)
- Frequency of database backups
- Number of standby databases required
Correct answer: Maximum acceptable duration of downtime after a failure event
RTO defines the maximum tolerable time from a failure event until business services are restored, directly driving high availability architecture decisions.
Question 6: Which RMAN command validates backup pieces and image copies without actually restoring them?
- RESTORE … PREVIEW
- VALIDATE BACKUPSET (Correct answer)
- CROSSCHECK BACKUP
- LIST BACKUP
Correct answer: VALIDATE BACKUPSET
VALIDATE BACKUPSET reads backup pieces and verifies block checksums to confirm that the backup is readable and internally consistent without performing an actual restore.
OCM OCM High Availability & Disaster Recovery 1
In Oracle Data Guard, which role does the primary database's standby perform when it actively processes redo in real time?