Understanding Ephemeral Storage in Amazon EC2
When managing your Amazon EC2 instances, it’s vital to understand the implications of ephemeral storage. This storage type can significantly influence how you design your infrastructure, especially regarding data persistence. Let’s unpack what ephemeral storage is and what you need to know to use it effectively.
What is Ephemeral Storage?
Ephemeral storage in AWS EC2 refers to temporary storage that is physically attached to the host computer running your instance. Upon stopping or terminating an instance, any data stored in the ephemeral storage will be lost. Such storage is ideal for temporary data that does not need to survive instance restarts, like caches, buffers, or other transient data processes.
Root Volume and Instance Store-Backed AMIs
When you launch an EC2 instance, you have two primary choices for the root device: instance store-backed AMIs and EBS-backed AMIs.
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Instance Store-Backed AMIs:
- The root volume is stored on ephemeral storage.
- Data on the root volume is lost when the instance is stopped or terminated.
- Best suited for use cases where you can afford to lose the data, or if you back up the necessary data elsewhere.
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EBS-Backed AMIs:
- The root volume is backed by Elastic Block Store (EBS), meaning data persists even after stopping and restarting the instance.
- Only if the instance is terminated will the data be lost, unless configured to keep the EBS volume.
Checking Your Instance’s Root Device Type
You might wonder whether your instance uses ephemeral or EBS-backed storage. Here’s how you can check:
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AWS Management Console:
- Navigate to EC2 -> Instances.
- Locate your instance in the list.
- Look at the “Root device type” column. If it says “ebs,” your root volume data will persist between reboots. If it says “instance store,” you are using ephemeral storage.
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Elastic Block Store:
- Go to EC2 -> Elastic Block Store -> Volumes.
- If your root volume appears in this list, it is EBS-backed.
Understanding the root device type is crucial for safeguarding your data. Before making any changes, ensure that critical data is stored on EBS or other persistent storage solutions.
Ephemeral storage is non-persistent whereas EBS provides persistence. It’s important to design your infrastructure and backup strategies according to your data durability needs. Always back up important data and understand the architectural requirements for using ephemeral storage efficiently.
For detailed information, you can refer to the AWS Documentation on Root Device Storage.