EC2 Instance Store
An instance store is temporary or Ephemeral block level storage that can be used to store an EC2 instance.
Storage for instance is located on disks that are physically attached the host computer.
Instance store is ideal to temporarily store information that changes frequently, such buffers, caches and scratch data, or data that is replicated across multiple instances such as a load-balanced group of web servers.
An instance store is made up of one or more instance stores volumes that are exposed as blocks devices.
The size of an instance store depends on the type of instance.
For instance, virtual devices store volumes that are ephemeral[0-23], and start the first one as ephemeral0.
Instance Store Lifecycle
The lifecycle of the Instance it is attached determines how long the Instance store data will last.
When an instance is restarted, data on the Instance store remains.
The data in the instance store will not persist if the underlying drive fails.
instance stops, i.e. If the EBS-backed instance with instance volume volumes attached is stopped
Instance Store Volumes
The instance type determines the size of the instance storage available and the type hardware used to store the volumes.
The hourly cost of an instance includes the volume of the instance store.
Instance Store Volumes using EC2 instances
Block device mapping is used to specify EBS volumes and instance storage volumes for an instance.
Only when an instance launches, can an instance store volume be attached to it.
The instance store volume cannot be separated and reattached in another instance.
Before an instance can be launched, it is necessary to format and mount the instance storage volumes.
Root volume of an instance store-backed instance is mounted automaticallyInstance Store Optimizing Writes
Because EC2 virtualizes disks in a way that slows down the initial write to any location on an instance storage volume, subsequent writes are more efficient.
This cost could be amortized (gradually written off) over the life of the instance.
AWS recommends that high disk performance be achieved by initializing drives by writing once at each drive location before production useEBS or Instance Store
Refer blog post @ EBS vs Instance Store
Questions for AWS Certification Exam Practice
Questions are collected via the Internet. The answers are marked according to my knowledge and understanding (which may differ from yours).
AWS services are constantly updated and the answers and questions may be out of date soon. So make sure to research accordingly.
AWS exam questions cannot be updated to keep up with AWS updates. This means that even if the underlying feature has been changed, the question may not be updated.
We are open to further discussion, feedback, and correction. Please select the most accurate answer regarding the persistence the Amazon Instance Store. The data on an instance store volume only persists during the lifetime of the associated Amazon EC2 instances
When the security group rule for the associated instance changes, the data on an instance storage volume is lost.
Even after an Amazon EC2 instance has been deleted, data from an instance store volume remains. A user has launched an EC2 instances from an AMI-backed instance store. The user has attached an instance store volume to the instance. The user wants to
EC2 Instance Store