Download Amazon Elastic Compute Cloud User Guide for Linux

Amazon Elastic Compute Cloud User Guide for Linux
Block Device Mapping Concepts
AMI has mappings for two instance store volumes, then the instance launches with one instance store
volume.
• Instance store volumes can only be mapped at launch time. You cannot stop an instance without
instance store volumes (such as the t2.micro), change the instance to a type that supports instance
store volumes, and then restart the instance with instance store volumes. However, you can create an
AMI from the instance and launch it on an instance type that supports instance store volumes, and
map those instance store volumes to the instance.
• If you launch an instance with instance store volumes mapped, and then stop the instance and change
it to an instance type with fewer instance store volumes and restart it, the instance store volume
mappings from the initial launch still show up in the instance metadata. However, only the maximum
number of supported instance store volumes for that instance type are available to the instance.
Note
When an instance is stopped, all data on the instance store volumes is lost.
• Depending on instance store capacity at launch time, M3 instances may ignore AMI instance store
block device mappings at launch unless they are specified at launch.You should specify instance store
block device mappings at launch time, even if the AMI you are launching has the instance store volumes
mapped in the AMI, to ensure that the instance store volumes are available when the instance launches.
Example Block Device Mapping
This figure shows an example block device mapping for an EBS-backed instance. It maps /dev/sdb to
ephemeral0 and maps two EBS volumes, one to /dev/sdh and the other to /dev/sdj. It also shows
the EBS volume that is the root device volume, /dev/sda1.
Note that this example block device mapping is used in the example commands and APIs in this topic.
You can find example commands and APIs that create block device mappings here:
• Specifying a Block Device Mapping for an AMI (p. 608)
• Updating the Block Device Mapping when Launching an Instance (p. 611)
API Version 2015-04-15
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