Amazon Elastic Compute Cloud
User Guide for Windows Instances

Amazon EBS and NVMe

With C5 and M5 instances, EBS volumes are exposed as NVMe block devices. The device names are /dev/nvme0n1, /dev/nvme1n1, and so on. The device names that you specify in a block device mapping are renamed using NVMe device names (/dev/nvme[0-26]n1).


The EBS performance guarantees stated in Amazon_EBS_Product_Details are valid regardless of the block-device interface.

Identifying the EBS Device

Windows AMIs

On C5 and M5 instances, EBS volumes are exposed as NVMe devices. You can use the Get-Disk command to map Windows disk numbers to EBS volume IDs.

PS C:\> Get-Disk |select Number,AdapterSerialNumber |Sort-Object Number Number AdapterSerialNumber ------ ------------------- 0 vol0064aexamplec838a 1 vol02256example8a4a3 2 vol0e4ceexample8bd5c 3 vol07063examplefb2cb 4 vol030edexample8a888

Working with NVMe EBS Volumes

If you resize your volume on a Windows system, you need to rescan the volume or reboot the instance for the change to be recognized.


If you are using st1 or sc1 volumes, we recommend that you continue to use C4 instances for now. C5 and M5 currently do not support st1 or sc1 volumes.

I/O Operation Timeout

NVMe EBS volumes use the default NVMe driver provided by the operating system. Most operating systems specify a timeout for I/O operations submitted to NVMe devices.

On Windows systems, the default timeout is 30 seconds and the maximum is 255 seconds. The TimeoutValue disk class registry setting can be modified using the procedure described in Registry Entries for SCSI Miniport Drivers.

On Linux systems, the default timeout is 30 seconds and can be changed using the nvme_core.io_timeout boot parameter. For an experience similar to EBS volumes attached to Xen instances, we recommend setting this to the maximum value possible. For Amazon Linux AMI 2017.09.01 (or greater), and for Linux kernels with version 4.15 or greater, the maximum is 4294967295. Prior to Linux 4.15, the maximum value is 255 seconds. If you are using a current version of the Amazon Linux AMI, we have already increased the timeout.