High Availability Flashcards
You need to provide high availability to RDS. How do you do that?
Build a multi-AZ RDS
What happens when the AZ that contains your RDS end point goes down?
RDS will update end point DNS and re-points to other AZ automatically
How does RDS multi AZ work?
It maintains two exact copies of your DB in two AZ’s
What are the advantages of RDS multi AZ?
high availability
backups and restores are taken from the secondary
How do you force a RDS failover?
reboot primary in console or using the rebootinstance API call
What are read replicas and what are they used for?
read only copy of DB
Used to scale beyond compute or I/O capacity of a single DB instance by serving read traffic from read only copies
How do you create a RDS read replica?
AWS console or CreateDBInstanceReadReplica
What RDS instance types support read replicas?
MySQL
postgres
MariaDB
Aurora
You’ve created a read replica. While being created users complain of performance issues. Why?
The RDS instance is not multi-az. If it was the read replica would have been created from the secondary instance.
How do you connect to read replica?
a new DNS endpoint is created
You have an RDS db and wish to create a dev copy. How can you do that?
Create a RR and promote the RR
How many read replicas can you have?
5
Can you have read replicas in different regions?
Yes
What is the key metric for read replicas?
REPLICA LAG
How can you tell what RDS version you are using>?
AWS console - details or CLI = aws rds describe-db-instance –region
What are the 4 key metrics to monitor for elasticache?
CPU ute
Swap ute
Evictions
Concurrent connections
What service should you use if you have performance issue on a read-heavy DB that is infrequently changed?
elasticache
What service should you use if you have performance issue on a DB that has many OLAP transactions?
Redshift
What are the two types of Aurora?
Aurora
Aurora Serveless
How many copies does Aurora maintain of your DB?
2 copies in 3 seperate AZ’s
What AWS RDS service is self healing?
Aurora
The Aurora CPU utilization is at 100% How do you resolve?
If it is writes causing the issue, scale up the instance size
If it is reads causing the issue, scale out by increasing the number of read replicas
You have an Aurora DB and need to ensure encryption at rest is enabled. How do you do that?
Encryption is turned on by default
How do you define the read replica fail-over order for Aurora?
Set the tier value
Will a new Aurora cluster be created in another region if cross region replication is enabled?
Yes
What are some reasons why auto scaling is not working?
Associated key pair does not exist
Sec group does not exist
Autoscaling config is not working
Instance type specified is not supported in the AZ
AZ is no longer supported
Invalid EBS device
Autoscaling service is not enabled on your account
Attempting to attach a service is not enabled on your account
Attempting to attach a EBS block device to an instance - store AMI
What are the maximum number of instances per AZ for a spread placement group
7
What failover option allows unhealthy instances to be redirected to active instances with minimal downtime?
active active
