Amazon Neptune | High Availability and Replication Flashcards
Can I share an encrypted Amazon Neptune snapshot?
High Availability and Replication
Amazon Neptune | Database
Yes, you can share encrypted Amazon Neptune snapshots.
How does Amazon Neptune improve my database’s fault tolerance to disk failures?
High Availability and Replication
Amazon Neptune | Database
Amazon Neptune automatically divides your database volume into 10GB segments spread across many disks. Each 10GB chunk of your database volume is replicated six ways, across three Availability Zones. Amazon Neptune is designed to transparently handle the loss of up to two copies of data without affecting database write availability and up to three copies without affecting read availability. Amazon Neptune storage is also self-healing. Data blocks and disks are continuously scanned for errors and repaired automatically.
How does Amazon Neptune improve recovery time after a database crash?
High Availability and Replication
Amazon Neptune | Database
Unlike other databases, after a database crash Amazon Neptune does not need to replay the redo log from the last database checkpoint (typically 5 minutes) and confirm that all changes have been applied, before making the database available for operations. This reduces database restart times to less than 60 seconds in most cases. Amazon Neptune moves the buffer cache out of the database process and makes it available immediately at restart time. This prevents you from having to throttle access until the cache is repopulated to avoid brownouts.
What kind of replicas does Neptune support?
High Availability and Replication
Amazon Neptune | Database
Amazon Neptune supports Read Replicas, which share the same underlying volume as the primary instance. Updates made by the primary are visible to all Amazon Neptune Replicas.
Feature Amazon Neptune Replicas
Number of replicas Up to 15
Replication Type Asynchronous (milliseconds)
Performance impact on primary Low
Act as failover target Yes (no data loss)
Automated failover Yes
Can I have cross-region replicas with Amazon Neptune?
High Availability and Replication
Amazon Neptune | Database
No, Amazon Neptune does not support cross-region replicas.
Can I prioritize certain replicas as failover targets over others?
High Availability and Replication
Amazon Neptune | Database
Yes. You can assign a promotion priority tier to each instance on your cluster. When the primary instance fails, Amazon Neptune will promote the replica with the highest priority to primary. If there is contention between 2 or more replicas in the same priority tier, then Amazon Neptune will promote the replica that is the same size as the primary instance.
Can I modify priority tiers for instances after they have been created?
High Availability and Replication
Amazon Neptune | Database
You can modify the priority tier for an instance at any time. Simply modifying priority tiers will not trigger a failover.
Can I prevent certain replicas from being promoted to the primary instance?
High Availability and Replication
Amazon Neptune | Database
You can assign lower priority tiers to replicas that you don’t want promoted to the primary instance. However, if the higher priority replicas on the cluster are unhealthy or unavailable for some reason, then Amazon RDS will promote the lower priority replica.
How can I improve upon the availability of a single Amazon Neptune database?
High Availability and Replication
Amazon Neptune | Database
You can add Amazon Neptune Replicas. Amazon Neptune Replicas share the same underlying storage as the primary instance. Any Amazon Neptune Replica can be promoted to become primary without any data loss and therefore can be used for enhancing fault tolerance in the event of a primary DB Instance failure. To increase database availability, simply create 1 to 15 replicas, in any of 3 AZs, and Amazon Neptune will automatically include them in failover primary selection in the event of a database outage.
What happens during failover and how long does it take?
High Availability and Replication
Amazon Neptune | Database
Failover is automatically handled by Amazon Neptune so that your applications can resume database operations as quickly as possible without manual administrative intervention.
If you have an Amazon Neptune Replica, in the same or a different Availability Zone, when failing over, Amazon Neptune flips the canonical name record (CNAME) for your DB primary endpoint to a healthy replica, which is in turn is promoted to become the new primary. Start-to-finish, failover typically completes within 30 seconds. Additionally, the read replicas endpoint doesn’t require any CNAME updates during failover.
If you do not have an Amazon Neptune Replica (i.e. single instance), Neptune will first attempt to create a new DB Instance in the same Availability Zone as the original instance. If unable to do so, Neptune will attempt to create a new DB Instance in a different Availability Zone. From start to finish, failover typically completes in under 15 minutes.
Your application should retry database requests in the event of connection loss.
If I have a primary database and an Amazon Neptune Replica actively taking read traffic and a failover occurs, what happens?
High Availability and Replication
Amazon Neptune | Database
Amazon Neptune will automatically detect a problem with your primary instance and begin routing your read/write traffic to an Amazon Neptune Replica. On average, this failover will complete within 30 seconds. In addition, the read traffic that your Amazon Neptune Replicas were serving will be briefly interrupted.
