sysops_notes.md

AWS SysOps Exam Tips

Monitoring

Cloudwatch

• What are the default host-level metrics for EC2?

  • CPU
  • Network
  • Disk
  • Status check

• What is the default time interval for EC2?

  • 5 minutes

• How long are Cloudwatch logs stored for by default?

  • Indefinitely

• What is the minimum granularity of custom metrics?

  • 1 minute

EBS

• What are the four storage types?

  • General Purpose (SSD) (gp2)
  • Provision-IOPS (SSD) io1
  • Throughput-Optimised (HDD) st1
  • Cold (HDD) sc1

• What are the maximum IOPS for gp2 storage?

  • 16000 IOPS

• Two important metrics for EBS are:

  • VolumeReadOps
  • VolumeWriteOps

• What does it mean when VolumeQueueLength is greater than zero?

  • You're maxing out your IOPS limit

ELB

• How can I see access logs of a terminated EC2 instance within an auto-scaling group?
  • Access logs should be enabled within the ELB.

Elasticache

• CPU utilisation

  • Memcached can handle loads of up to 90%. If it exceeds 90% add more nodes
  • To determine when to scale Redis, take 90 and divide it by the number of cores

• Swap usage

  • Memcached - should be zero and should not exceed 50mb. If it does, then increase the memcached_connections_overhead parameter.
  • Redis uses reserved-memory metric instead

• Evictions

  • Memcached - choose a threshold based off your application. Must scale up
  • Redis - same as above. Can either scale up or out.

• Concurrent connections

  • Memcached & Redis
    • No recommended setting and is based off your application.
    • An alarm should be set on the number of concurrent connections for Elasticache.

Cost Explorer

• Use tags to tag resources
• Activate cost allocation tags to track costs and generate reports
• Use Resource Manager to group tags into resource groups

RDS

• How do you encrypt an existing RDS instance?

  • Take a snapshot of it
  • Copy the snap to the same or different region
  • Encrypt the copy during the copy process
  • Restore from this newly-encrypted snapshot

• Can you share encrypted snapshots between accounts?

  • Create a custom KMS encryption key
  • Create an RDS snapshot using this custom key
  • Share the custom KMS encryption key that was used to encrypt the snapshot
  • Use the AWS Management console, CLI or RDS API to share the encrypted snapshot with the other accounts

Maintenance Windows

• Which services have maintenance windows?

  • RDS
  • Elasticache
  • Redshift
  • DynamoDB DAX
  • Neptune
  • Amazon DocumentDB

• Which services do not have maintenance windows?

  • EC2
  • Lambda
  • Amazon QLDB