this Question is very Old and should be deleted from the exam , there is no Failover replica now , to do an HA we just confer it for the SQL instance that we have .
https://cloud.google.com/sql/docs/mysql/replication#:~:text=Read%20replicas%20neither%20provide%20high%20availability%20nor%20offer%20it.&text=A%20primary%20instance%20cannot%20failover,any%20way%20during%20an%20outage.&text=Maintenance%20windows%20cannot%20be%20set,windows%20with%20the%20primary%20instance.
- Read replicas neither provide high availability nor offer it.
Agree D
That link is helpful! I navigated to the "quick reference for Cloud SQL read replicas" and read the "failover" and "high availability" topics. They state:
1. Failover - "A primary instance cannot failover to a read replica, and read replicas are unable to failover in any way during an outage."
2. High Availability - "Read replicas neither provide high availability nor offer it."
Sorry for this, but in the same link you can read:
High availability Read replicas allow you to enable high availability on the replicas.
(What I understand is that Read Replicas give you high availability on reads, of course, not in writes).
Cloud SQL is regional. For high availability, we need to think fo a failover strategy. So Option D meets the requirement.
create failover replica in the same region but in different Zone
Answer is D:
Create a failover replica instance in the same region, but in a different zone.
Here’s why this option is the best:
1. High Availability: A failover replica provides automatic failover capabilities, meaning that if the primary instance becomes unavailable (due to a zone failure, for example), Cloud SQL can automatically promote the failover replica to be the new primary instance, minimizing downtime.
2. Same Region, Different Zone: By creating the failover replica in the same region but a different zone, you ensure that the instances are geographically close to each other, which helps maintain low latency and faster failover times while still protecting against zone-specific outages.
3. Cost Efficiency: Using a failover replica in the same region is typically more cost-effective than setting up a replica in a different region, as cross-region replication can introduce additional latency and costs.
The HA configuration provides data redundancy. A Cloud SQL instance configured for HA is also called a regional instance and has a primary and secondary zone within the configured region. Within a regional instance, the configuration is made up of a primary instance and a standby instance. Through synchronous replication to each zone's persistent disk, all writes made to the primary instance are replicated to disks in both zones before a transaction is reported as committed. In the event of an instance or zone failure, the standby instance becomes the new primary instance. Users are then rerouted to the new primary instance. This process is called a failover.
https://cloud.google.com/sql/docs/mysql/high-availability#HA-configuration
"Note: Read replicas do not provide failover capability. To provide failover capability for an instance, see Configuring an instance for high availability."
https://cloud.google.com/sql/docs/mysql/replication/
Correct answer would be D as a failover replica acts as a redundant copy incase of zone failure. However, option C causes confusion because a read replica can provide availability for reads, in case of zone failure for primary, but they cant provide support for writes. They would only work for reads.
C
1. Failover replica is a legacy way and is not available in GCP now - B and D are not the options: https://cloud.google.com/sql/docs/mysql/high-availability#legacy_mysql_high_availability_option
2. Cloud SQL is regional resource. However, cross-region read replicas are allowed now in Cloud SQL (https://cloud.google.com/blog/products/databases/introducing-cross-region-replica-for-cloud-sql) - A and C are options.
Chosen C, as there is no requirement or mention of cross-regional / global db.
Read replica is not a valid choice for HA configurations. It does not provide automatic failover that is required for HA. It may be called something different or this answer has changed, but D is still the best option.
D.
In HA config, the second replica is caled stand by. The process of replacing the primary damaged node is called failover.
https://cloud.google.com/sql/docs/postgres/high-availability
this Question is very Old and should be deleted from the exam , there is no Failover replica now , to do an HA we just confer it for the SQL instance that we have .. agreed tested as well
Option C is not the best choice because it suggests creating a read replica instance, which is designed to handle read traffic and provide better performance in read-heavy workloads, but it is not intended for high availability.
On the other hand, Option D suggests creating a failover replica instance in the same region but in a different zone. Failover replicas are designed specifically for high availability, as they maintain an up-to-date copy of the primary instance's data. If the primary instance becomes unresponsive or fails, Cloud SQL automatically switches to the failover replica with minimal downtime.
In summary, to introduce high availability for your Cloud SQL instance, you should create a failover replica instance in the same region but in a different zone (Option D) rather than creating a read replica instance (Option C), which doesn't provide high availability in case of primary instance failures.
D
C is also not ideal for high availability because creating a read replica in the same region but in a different zone does not provide automatic failover. A read replica is used for scaling reads and can improve performance, but it is not a failover mechanism.
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