Many customers, as well as services like Amazon Aurora, build highly durable and available systems on local instance storage. Still, there is a misconception that data on local instance store volumes (both the more "classic" HDD or SSD volumes that are virtualized by Xen, as well as the new generation of local NVMe storage) could vanish due to this vestigial term that lingers in the API. By 2010 we had transitioned to using "instance storage" in the documentation, which included a big note about how the data remains if an instance reboots for any reason (planned or unplanned). Data written to local storage is not transient, fleeting, or short lived. The "ephemeral" term confuses a lot of customers, and that's why we stopped using it. ![]() I don't know exactly when we stopped using "ephemeral" in our documentation, but I think it was with the introduction of EBS around 2008. Unfortunately it is part of the EC2 API for the block device mapping of the "classic" instance store interfaces on the Xen platform. Additionally, Windows instances will format the instance store volumes to NTFS (although, by default, the volumes come formatted as ext3).ĪWS details the available instance storage and allocations in their documentation.The "ephemeral" term is a legacy. Note, on windows instance, you will specify the device as /dev/xvdX, whereas on Linux instances you will specify it as /dev/sdX (although, modern Linux kernels will still show this device as /dev/xvdX, with a symlink to /dev/sdX). ![]() Register a new AMI, explicitly specifying the ephemeral disk mappings (and an EBS root): ec2-register -n Image_Name -d Image_Description -root-device-name /dev/xvda1 -b /dev/xvda1=snap-xxxxxxxx -b /dev/xvdb=ephemeral0 -b /dev/xvdc=ephemeral1 -b /dev/xvdd=ephemeral2 -b /dev/xvde=ephemeral3 Launch the instance explicitly specifying the ephemeral disk mappings OR ec2-run-instances ami-xxxxxxxx -b /dev/xvdb=ephemeral0 -b /dev/xvdc=ephemeral1 -b /dev/xvdd=ephemeral2 -b /dev/xvde=ephemeral3 In order to change the ephemeral disks attached to the instance, you need to either: Since ephemeral disks, together with EBS volumes, are block devices, AWS calls the mapping of these disks to an instance's devices 'block device mappings', and these can be specified either using the -b or -block-device-mapping parameters (which you can use more than once). (On the other hand, you can add EBS volumes to an instance while it is running). You can NOT attach these to an instance once it has been launched. The ephemeral disks, available to an instance are labelled ephemeral. But Aws recommends using EBS storage-backed AMIS as they get launched faster and. Each option has a unique combination of performance and durability. Instances can either be launched with Elastic block storage volume (EBS volume) or Instance store-backed volumes as to their root volumes. In most cases, instances with an EBS root volume will have zero or one attached ephemeral volumes. EC2 basically provides two types of block-level storage. An instance store provides temporary (ephemeral) block-level storage for your instance. When I Start the instance, I can login and use the Window's Disk Management tool to mount my Instance Storage as a drive letter. When you use an Amazon EC2 instance store, use the instance store volume for tempdb. ![]() I want to use the ephemeral Instance Storage. ephemeral storage), that storage is not necessarily attached by default. I have an AWS EC2 instance based on an Amazon-provided AMI for Microsoft Windows Server 2016. While all instances, other than the t1.micro, do have an allocation of 'instance storage' (i.e.
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