Attaching a Volume to an Instance

This section describes how to attach a volume that you created to an instance.

The following table lists the available device names on Amazon EC2. You can specify these names when attaching a volume to a running instance or when attaching a volume when launching an instance using a block device mapping. The block device driver for the instance assigns the actual volume names when mounting the volumes, and these names can be different than the names that Amazon EC2 recommends. For more information about the instance store, see Amazon EC2 Instance Store. For information about the root device storage, see Amazon EC2 Root Device Volume.

After you have mapped a device using one of these device names, it is mapped to either a scsi drive (sd[a-z]) or an xvd drive (xvd[a-p]), depending on the block device driver of your kernel. If the kernel has an xvd driver, the device is mapped to xvd[a-p]. If the kernel doesn't have an xvd driver, the device is mapped to sd[a-z][1-15].

Base Windows and CentOS HPC (Cluster Compute) images come bundled with an xvd driver, so the devices on Windows and CentOS HPC (Cluster Compute) instances are mapped to xvd[a-p]. The xvd drivers (xvd[a-p]) don't support the use of trailing numbers (xvd[a-p][1-15]). We recommend that you use device names to xvd[a-p] on instances that have xvd drivers.

Depending on the size of your instance, Amazon EC2 provides instance store volumes on sd[b-e] (on Linux/UNIX) or xvd[a-e] (on Windows and CentOS HPC). Although you can connect your Amazon EBS volumes using these device names, we highly recommend that you don't because the behavior can be unpredictable.

An Amazon EC2 Windows AMI comes with an additional service installed, the Ec2Config Service. The Ec2Config Service runs as a local system and performs various functions to prepare an instance when it first boots up. After the devices have been mapped with the drives, the Ec2Config Service then initializes and mounts the drives. The root drive is initialized and mounted as c:\. The instance stores that comes attached to the instance are initialized and mounted as d:\, e:\, and so on. By default, when an EBS volume is attached to a Windows instance, it may show up as any drive letter on the instance. You can change the settings of the Ec2Config Service to set the drive letters of the EBS volumes per your specifications. For more information, go to Using Ec2Config in the Amazon Elastic Compute Cloud Microsoft Windows Guide.

PROMPT>  ec2-attach-volume volume_id -i instance_id -d device

ATTACHMENT volume_id instance_id device attaching date_time 

PROMPT>  ec2-attach-volume vol-4d826724 -i i-6058a509 -d /dev/sdh

ATTACHMENT vol-4d826724 i-6058a509 /dev/sdh attaching 2010-03-30T13:58:58+0000 

PROMPT>  ec2-attach-volume vol-4d826724 -i i-6058a509 -d xvdf

ATTACHMENT vol-4d826724 i-6058a509 xvdf attaching 2010-03-30T13:58:58+0000 

https://ec2.amazonaws.com/
?Action=AttachVolume
&VolumeId=volume-id
&InstanceId=instance-id
&Device=device
&AUTHPARAMS

<AttachVolumeResponse xmlns="http://ec2.amazonaws.com/doc/2013-02-01/">
  <requestId>59dbff89-35bd-4eac-99ed-be587EXAMPLE</requestId> 
  <volumeId>vol-4d826724</volumeId>
  <instanceId>i-6058a509</instanceId>
  <device>/dev/sdh</device>
  <status>attaching</status>
  <attachTime>2008-05-07T11:51:50.000Z</attachTime>
</AttachVolumeResponse>