Specifies a block device mapping for an instance. You must specify exactly one of the
following properties: VirtualName, Ebs, or
NoDevice.
BlockDeviceMapping is a property of the AWS::EC2::Instance resource.
Important
After the instance is running, you can modify only the
DeleteOnTermination parameter for the attached volumes without
interrupting the instance. Modifying any other parameter results in instance replacement.
Syntax
To declare this entity in your AWS CloudFormation template, use the following syntax:
JSON
{
"DeviceName" : String,
"Ebs" : Ebs,
"NoDevice" : Json,
"VirtualName" : String
}
YAML
DeviceName: String
Ebs:
Ebs
NoDevice: Json
VirtualName: String
Properties
DeviceName-
The device name (for example,
/dev/sdhorxvdh).Important
After the instance is running, this parameter is used to specify the device name of the block device mapping to update.
Required: Yes
Type: String
Update requires: Some interruptions
Ebs-
Parameters used to automatically set up EBS volumes when the instance is launched.
Important
After the instance is running, you can modify only the
DeleteOnTerminationparameter for the attached volumes without interrupting the instance. Modifying any other parameter results in instance replacement.Required: Conditional
Type: Ebs
Update requires: Some interruptions
NoDevice-
To omit the device from the block device mapping, specify an empty string.
Important
After the instance is running, modifying this parameter results in instance replacement.
Required: Conditional
Type: Json
Update requires: Some interruptions
VirtualName-
The virtual device name (
ephemeralN). The name must be in the formephemeralX where X is a number starting from zero (0). For example, an instance type with 2 available instance store volumes can specify mappings forephemeral0andephemeral1. The number of available instance store volumes depends on the instance type. After you connect to the instance, you must mount the volume.NVMe instance store volumes are automatically enumerated and assigned a device name. Including them in your block device mapping has no effect.
Constraints: For M3 instances, you must specify instance store volumes in the block device mapping for the instance. When you launch an M3 instance, we ignore any instance store volumes specified in the block device mapping for the AMI.
Important
After the instance is running, modifying this parameter results in instance replacement.
Required: Conditional
Type: String
Update requires: Some interruptions
Examples
Block device mapping with two EBS volumes
This example sets the EBS-backed root device (/dev/sda1) size to 50 GiB, and another EBS-backed device mapped to /dev/sdm that is 100 GiB in size.
JSON
"BlockDeviceMappings" : [
{
"DeviceName" : "/dev/sda1",
"Ebs" : { "VolumeSize" : "50" }
},
{
"DeviceName" : "/dev/sdm",
"Ebs" : { "VolumeSize" : "100" }
}
]YAML
BlockDeviceMappings:
- DeviceName: /dev/sda1
Ebs:
VolumeSize: 50
- DeviceName: /dev/sdm
Ebs:
VolumeSize: 100Block device mapping with an instance store volume
This example maps an instance store volume to device /dev/sdc.
JSON
"BlockDeviceMappings" : [
{
"DeviceName" : "/dev/sdc",
"VirtualName" : "ephemeral0"
}
]YAML
BlockDeviceMappings:
- DeviceName: /dev/sdc
VirtualName: ephemeral0Unmap an AMI-defined device
To unmap a device defined in the AMI, set the NoDevice property to an
empty map, as shown here:
JSON
"BlockDeviceMappings" : [
{
"DeviceName":"/dev/sde",
"NoDevice": {}
}
]YAML
BlockDeviceMappings:
- DeviceName: /dev/sde
NoDevice: {}See also
-
Block device mappings in the Amazon EC2 User Guide.
