AWS EC2 Instance Lifecycle

Overview

  • An instance is a virtual server in the AWS cloud.You launch an instance from an Amazon Machine Image (AMI).
  • AMI provides the operating system, application server, and applications for your instance.
  • When an instance is launched, it receives a public DNS name that can be used to contact the instance from the Internet. Instance also receives a private DNS name that other instances within the same Amazon EC2 network can use to contact the instance

Instance Lifecycle

EC2 Instance Lifecycle

  • Pending
    • When the instance is first launched is enters into the pending state
  • Running
    • After the instance is launched, it enters into the running state
    • Charges are incurred for every hour or partial hour the instance is running even if it is idle
  • Start & Stop (EBS-backed instances only)
    • Only and EBS-backed instance can be stopped and started. Instance store-bakced instance cannot be stopped and started
    • An instance can stopped & started in case the instance fails a status check or is not running as expected
    • Stop
      • After the instance is stopped, it enters in stopping state and then to stopped state.
      • Charges are only incurred for the EBS storage and not for the instance hourly charge or data transfer.
      • While the instance is stopped, you can treat its root volume like any other volume, and modify it for e.g. repair file system problems or update software or change the instance type, user data, EBS otpmization attributes etc
      • Volume can be detached from the stopped instance, and attached to a running instance, modified, detached from the running instance, and then reattached to the stopped instance. It should be reattached using the storage device name that’s specified as the root device in the block device mapping for the instance.
    • Start
      • When the instance is started, it enters into pending state and then into running
      • An instance when stopped and started is launched on a new host
      • Any data on an instance store volume (not root volume) would be lost while data on the EBS volume persists
    • EC2 instance retains its private IP address as well as the Elastic IP address. However, the public IP address, if assigned instead of the Elastic IP address, would be released
    • Charges for full hour are incurred for every transition from stopped to running, even if the transition is within the same hour for e.g. if you stop and start your instances 2 times in an hour, you would be charged for 3 full hours, one for the start and then for the 2 transitions as if you had 3 instances running during that hour
  • Instance reboot
    • Both EBS-backed and Instance store-backed instances can be rebooted
    • An instance retains it public DNS, public and private IP address during the reboot
    • Data on the EBS and Instance store volume is also retained
    • Amazon recommends to use Amazon EC2 to reboot the instance instead of running the operating system reboot command from your instance as it performs a hard reboot if the instance does not cleanly shutdown within four minutes also creates an API record in CloudTrail, if enabled.
  • Instance retirement
    • An instance is scheduled to be retired when AWS detects irreparable failure of the underlying hardware hosting the instance.
    • When an instance reaches its scheduled retirement date, it is stopped or terminated by AWS.
    • If the instance root device is an Amazon EBS volume, the instance is stopped, and can be started again at any time.
    • If the instance root device is an instance store volume, the instance is terminated, and cannot be used again.
  • Instance Termination
    • An instance can be terminated, and it enters into the shutting-down and then the terminated state
    • After an instance is terminated, it can’t be connected and no charges are incurred
    • Instance Shutdown behaviour
      • EBS-backed instance supports InstanceInitiatedShutdownBehavior attribute which determines whether the instance would be stopped or terminated when a shutdown command is initiated from the instance itself for e.g. shutdown, halt or poweroff command in linux.
      • Default behaviour for the the instance to be stopped.
      • A shutdown command for an Instance store-backed instance will always terminate the instance
    • Termination protection
      • Termination protection (DisableApiTermination attribute) can be enabled on the instance to prevent it from being accidently terminated
      • DisableApiTerminationfrom the Console, CLI or API.
      • Instance can be terminated through Amazon EC2 CLI.
      • Termination protection does not work for instances when
        • part of an Autoscaling group
        • launched as Spot instances
        • terminating an instance by initiating shutdown from the instance
    • Data persistence
      • EBS volume have a DeleteOnTermination attribute which determines whether the volumes would be persisted or deleted when an instance they are associated with are terminated
      • Data on Instance store volume data does not persist
      • Data on EBS root volumes, have the DeleteOnTermination flag set to true, would be deleted by default
      • Additional EBS volumes attached have the DeleteOnTermination flag set to false are not deleted but just dettached from the instance

Screen Shot 2016-04-30 at 7.16.00 AM.png

AWS Certification Exam Practice Questions

  • Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
  • AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
  • AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
  • Open to further feedback, discussion and correction.
  1. What does Amazon EC2 provide?
    1. Virtual servers in the Cloud
    2. A platform to run code (Java, PHP, Python), paying on an hourly basis.
    3. Computer Clusters in the Cloud.
    4. Physical servers, remotely managed by the customer.
  2. A user has enabled termination protection on an EC2 instance. The user has also set Instance initiated shutdown behavior to terminate. When the user shuts down the instance from the OS, what will happen?
    1. The OS will shutdown but the instance will not be terminated due to protection
    2. It will terminate the instance
    3. It will not allow the user to shutdown the instance from the OS
    4. It is not possible to set the termination protection when an Instance initiated shutdown is set to Terminate
  3. A user has launched an EC2 instance and deployed a production application in it. The user wants to prohibit any mistakes from the production team to avoid accidental termination. How can the user achieve this?
    1. The user can the set DisableApiTermination attribute to avoid accidental termination
    2. It is not possible to avoid accidental termination
    3. The user can set the Deletion termination flag to avoid accidental termination
    4. The user can set the InstanceInitiatedShutdownBehavior flag to avoid accidental termination
  4. You have been doing a lot of testing of your VPC Network by deliberately failing EC2 instances to test whether instances are failing over properly. Your customer who will be paying the AWS bill for all this asks you if he being charged for all these instances. You try to explain to him how the billing works on EC2 instances to the best of your knowledge. What would be an appropriate response to give to the customer in regards to this?
    1. Billing commences when Amazon EC2 AMI instance is completely up and billing ends as soon as the instance starts to shutdown.
    2. Billing commences when Amazon EC2 initiates the boot sequence of an AMI instance and billing ends when the instance shuts down.
    3. Billing only commences only after 1 hour of uptime and billing ends when the instance terminates.
    4. Billing commences when Amazon EC2 initiates the boot sequence of an AMI instance and billing ends as soon as the instance starts to shutdown.

References

AWS S3 Object Lifecycle Management – Certification

S3 Object Lifecycle Overview

  • S3 Object lifecycle can be managed by using a lifecycle configuration, which defines how S3 manages objects during their lifetime.
  • Lifecycle configuration enables simplification of object lifecycle management, for e.g. moving of less frequently access objects, backup or archival of data for several years or permanent deletion of objects, all transitions can be controlled automatically
  • 1000 lifecycle rules can be configured per bucket
  • S3 Object Lifecycle Management rules applied to an bucket are applicable to all the existing objects in the bucket as well as the ones that will be added anew
  • S3 Object lifecycle management allows 2 types of behavior
    • Transition in which the storage class for the objects change
    • Expiration where the objects are permanently deleted
  • Lifecycle Management can be configured with Versioning, which allows storage of one current object version and zero or more non current object versions
  • Object’s lifecycle management applies to both Non Versioning and Versioning enabled buckets
  • For Non Versioned buckets
    • Transitioning period is considered from the object’s creation date
  • For Versioned buckets,
    • Transitioning period for current object is calculated for the object creation date
    • Transitioning period for non current object is calculated for the date when the object became a noncurrent versioned object
    • S3 uses the number of days since its successor was created as the number of days an object is noncurrent.
  • S3 calculates the time by adding the number of days specified in the rule to the object creation time and rounding the resulting time to the next day midnight UTC. For e.g., if an object was created at 15/1/2016 10:30 AM UTC and you specify 3 days in a transition rule, which results in 18/1/2016 10:30 AM UTC and rounded of to next day midnight time 19/1/2016 00:00 UTC.
  • Lifecycle configuration on MFA-enabled buckets is not supported.

S3 Object Lifecycle Management Rules

  1. STANDARD or REDUCED_REDUNDANCY -> (128 KB & 30 days) -> STANDARD_IA
    • Only objects with size more than 128 KB can be transitioned, as cost benefits for transitioning to STANDARD_IA can be realized only for larger objects
    • Objects must be stored for at least 30 days in the current storage class before being transitioned to the STANDARD_IA, as younger objects are accessed more frequently or deleted sooner than is suitable for STANDARD_IA
  2. STANDARD_IA -> X -> STANDARD or REDUCED_REDUNDANCY
    • Cannot transition from STANDARD_IA to STANDARD or REDUCED_REDUNDANCY
  3. STANDARD or REDUCED_REDUNDANCY or STANDARD_IA -> GLACIER
    • Any Storage class can be transitioned to GLACIER
  4. STANDARD or REDUCED_REDUNDANCY -> (1 day) -> GLACIER
    • Transitioning from Standard or RRS to Glacier can be done in a day
  5. STANDARD_IA -> (30 days) -> GLACIER
    • Transitioning from Standard IA to Glacier can be done only after 30 days or 60 days from the object creation date or non current version date
  6. GLACIER-> X -> STANDARD or REDUCED_REDUNDANCY or STANDARD_IA
    • Transition of objects to the GLACIER storage class is one-way
    • Cannot transition from GLACIER to any other storage class.
  7. GLACIER -> (90 days) -> Permanent Deletion
    • Deleting data that is archived to Glacier is free, if the objects you delete are archived for three months or longer.
    • Amazon S3 charges a prorated early deletion fee, if the object is deleted or overwritten within three months of archiving it.
  8. STANDARD or STANDARD_IA or GLACIER -> X-> REDUCED_REDUNDANCY
    • Cannot transition from any storage class to REDUCED_REDUNDANCY.
  9. Archival of objects to Amazon Glacier by using object lifecycle management is performed asynchronously and there may be a delay between the transition date in the lifecycle configuration rule and the date of the physical transition. However, AWS charges Amazon Glacier prices based on the transition date specified in the rule
  10. For a versioning-enabled bucket
    • Transition and Expiration actions apply to current versions.
    • NoncurrentVersionTransition and NoncurrentVersionExpiration actions apply to noncurrent versions and works similar to the non versioned objects except the time period is from the time the objects became noncurrent
  11. Expiration Rules
    • For Non Versioned bucket
      • Object is permanently deleted
    • For Versioned bucket
      • Expiration is applicable to the Current object only and does not impact any of the non current objects
      • S3 will insert a Delete Marker object with unique id and the previous current object becomes a non current version
      • S3 will not take any action if the Current object is a Delete Marker
      • If the bucket has a single object which is the Delete Marker (referred to as expired object delete marker), S3 removes the Delete Marker
    • For Versioned Suspended bucket
      • S3 will insert a Delete Marker object with version ID null and overwrite the any object with version ID null
  12. When an object reaches the end of its lifetime, Amazon S3 queues it for removal and removes it asynchronously. There may be a delay between the expiration date and the date at which S3 removes an object.You are not charged for storage time associated with an object that has expired.
  13. There are additional cost considerations if you put lifecycle policy to expire objects that have been in STANDARD_IA for less than 30 days, or GLACIER for less than 90 days.

AWS Certification Exam Practice Questions

  • Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
  • AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
  • AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
  • Open to further feedback, discussion and correction.
  1. Your firm has uploaded a large amount of aerial image data to S3. In the past, in your on-premises environment, you used a dedicated group of servers to oaten process this data and used Rabbit MQ, an open source messaging system, to get job information to the servers. Once processed the data would go to tape and be shipped offsite. Your manager told you to stay with the current design, and leverage AWS archival storage and messaging services to minimize cost. Which is correct?
    1. Use SQS for passing job messages, use Cloud Watch alarms to terminate EC2 worker instances when they become idle. Once data is processed, change the storage class of the S3 objects to Reduced Redundancy Storage (Need to replace On-Premises Tape functionality)
    2. Setup Auto-Scaled workers triggered by queue depth that use spot instances to process messages in SQS. Once data is processed, change the storage class of the S3 objects to Reduced Redundancy Storage (Need to replace On-Premises Tape functionality)
    3. Setup Auto-Scaled workers triggered by queue depth that use spot instances to process messages in SQS. Once data is processed, change the storage class of the S3 objects to Glacier (Glacier suitable for Tape backup)
    4. Use SNS to pass job messages use Cloud Watch alarms to terminate spot worker instances when they become idle. Once data is processed, change the storage class of the S3 object to Glacier.
  2. You have a proprietary data store on-premises that must be backed up daily by dumping the data store contents to a single compressed 50GB file and sending the file to AWS. Your SLAs state that any dump file backed up within the past 7 days can be retrieved within 2 hours. Your compliance department has stated that all data must be held indefinitely. The time required to restore the data store from a backup is approximately 1 hour. Your on-premise network connection is capable of sustaining 1gbps to AWS. Which backup methods to AWS would be most cost-effective while still meeting all of your requirements?
    1. Send the daily backup files to Glacier immediately after being generated (will not meet the RTO)
    2. Transfer the daily backup files to an EBS volume in AWS and take daily snapshots of the volume (Not cost effective)
    3. Transfer the daily backup files to S3 and use appropriate bucket lifecycle policies to send to Glacier (Store in S3 for seven days and then archive to Glacier)
    4. Host the backup files on a Storage Gateway with Gateway-Cached Volumes and take daily snapshots (Not Cost effective as local storage as well as S3 storage)