What are the 3 strategies available for Placement Groups?
- Cluster
- Spread
- Partition
What is the Cluster Strategy?
It clusters instances into a low latency group in a single AZ - High performance but high risk
What is the Spread Strategy?
It spreads instances across underlying hardware, with a max of 7 instances per AZ. - For critical apps
Whats is the Partition Strategy?
Like Spread but relies on different sets of hardware racks in an AZ. Can scale to hundreds of EC2 instances per group and is good for Hadoop etc.
What would I use a Cluster Placement Group for?
- Big Data job that needs to complete fast
- App that needs low latency and high network throughout
What would I use a Spread Placement Group for?
- App that needs to maximize high availability
- Critical apps where instances need to be separated from each other
What would I use a Partition Placement Group for?
HDFS, HBase, Cassandra, Kafka
What happens if you have an instance that has termination protection enabled but shutdown behavior set to terminate?
If the shutdown command is run from the cli, the shutdown behavior will override the protections
What does an InstanceLimitExceeded error mean?
You have reached the max number of instances allowed per region
What is the default max number of instances per region?
20
What does an InsuficcientInstanceCapacity error mean?
That AWS does not have the on-demand capacity in this region right now
What are the 4 possible reasons an instance would terminate immediately? (go from pending to terminated)
- You’ve reached your EBS volume limit
- An EBS Snapshot is corrupt
- The root EBS volume is encrypted and you dont have permissions to access the KMS key for decryption
- The instance store backed AMI that you used is missing a required part.
While SSH’ing into an instance, why would I get an “Unprotected Private Key File” error?
If the pem file does not have 400 permissions.
While SSH’ing into an instance, why would I get an “Host key not found” error?
The incorrect username for the OS was given.
What are the 2 possible reasons for a connection timeout while ssh into an instance?
- Security Group is not configured correctly
- CPU load of instance is too high
What are the 11 EC2 instance types?
F - Field Programmable Gateway I - IOPS G - Graphics H - High Disk Throughput T - Cheap Genreal Purpose D - Density R - RAM M - Main option for Genral Purpose C - Compute P - Graphics (pics) X - Extreme Memory
For Basic Monitoring in Cloudwatch, at what interval are metrics collected?
5 minute interval
For Detailed Monitoring in Cloudwatch, at what interval are metrics collected?
1 minute interval
What 4 metrics are included by default?
- CPU
- Network
- Disk
- Status Checks
What is the basic resolution for a Custom Metric?
1 minute Resolution
What is the high resolution for a Custom Metric?
Up to 1 second
