RDS & Using Read Replicas Flashcards
What are read replicas?
Read-only copies of your DB that allow you to scale out for performance.
How can a read replica be created?
- Management console
2. CreateDBInstanceReadReplica API
Can you have a read replica of a read replica?
Yes, but there may be latency.
Would you use a read replica to scale beyond your primary DB’s capacity?
Yes
Would you use a read replica to serve traffic while the primary DB is unavailable?
Yes
True or False: When running business reports, and performing data warehousing operations, it is best practice to use your primary DB instance?
False. Utilize read replicas for data-intensive workloads so the application is not affected.
True or false: You could also import your data into RedShift for data warehousing operations to prevent load on the application DB?
True.
Read replicas are supported on which non-Aurora databases?
MySQL
PostgreSQL
MariaDB
True or False: Amazon uses a proprietary replication engine for read-replicas?
False. Amazon uses the native replication engines built into their supported DBs for read-replicas.
True or False: Aurora uses SSD-Backed virtualized storage layer built for database workloads?
True
What does AWS do when a read replica is created?
Takes a snapshot of your DB
When creating a read replica, if multi-AZ is not enabled, what will the snapshot be of?
The primary DB.
True or False: When a snapshot is made of the primary DB, there is a suspension of I/O for 1 minute?
True
When creating a read replica, if multi-AZ is enabled, what will the snapshot be of?
Of the secondary database
True or False: When a snapshot is made of the secondary DB, there is a suspension of I/O for 30 seconds?
False. Since the snapshot is not being made of the primary (production) DB, there is no I/O suspension
True or False: Read replicas are accessed from the DNS of the primary DB?
False. You are given a new end point.
True or false: Read replicas are a new end point, different from the primary and secondary DB (If multi-AZ is enabled)
True.
Can you promote a read replica to be its own standalone DB?
Yes
What will happen to the primary and secondary DB if a read replica is promoted?
replication will break.
Up to how many read replicas per DB are supported?
5
True or False: You can have read replicas in different regions?
True
Read replica replications are synchronous, or asynchronus?
asynchronous.
Multi-AZ DB replications are synchronous, or asynchronus?
synchronous
Can read replicas be built off Multi-AZ DB?
Yes, this saves on performance impact.
Can read replicas be multi-AZ?
Yes. This is a new service.
Can DB snapshots be taken of read replicas?
No. Must use Mult-AZ to offload snapshot I/O performance hit
Can automated backups be taken of read replicas?
No. Must use Mult-AZ to offload I/O performance hit
Key metric to look for in read replicas?
REPLICA LAG
What is replica lag?
The replication latency. The amount of time it takes for a write to the primary DB to replicate to the read replica DB.
What is the difference between read replica and Multi-AZ?
- Read replica is a read only copy of your primary DB and is used for performance and scalability.
- Multi-AZ is for fail over only, and does not provide performance increases.
Can you create a read replica if DB backups are disabled?
No. Backups must be enabled to use read replicas.
When applying a modification to a DB, what two options are available for when the changes should be made?
- During the maintenance window.
2. Apply Immediately.
True or False: When immediately applying a modification, any modifications that are scheduled within the normal maintenance window will also be executed?
True. Be careful when applying changes immediately. If you’re making a modification that you don’t expect will cause downtime, you may have a scheduled task that does cause downtime, which may lead to unscheduled outages.
True or false: A read replica instance type can be different from the primary DB
True.
True or false. If the primary DB is gp1, the read replica must also be gp1?
False. You have the option of selecting gp1, io1, or magnetic.
