Amazon EC2 | Enhanced Networking Flashcards
How do EBS volumes behave when accessed by NVMe interfaces?
Enhanced Networking
Amazon EC2 | Compute
There are some important differences in how operating system NVMe drivers behave compared to Xen paravirtual (PV) block drivers.
First, the NVMe device names used by Linux based operating systems will be different than the parameters for EBS volume attachment requests and block device mapping entries such as /dev/xvda and /dev/xvdf. NVMe devices are enumerated by the operating system as /dev/nvme0n1, /dev/nvme1n1, and so on. The NVMe device names are not persistent mappings to volumes, therefore other methods like file system UUIDs or labels should be used when configuring the automatic mounting of file systems or other startup activities. When EBS volumes are accessed via the NVMe interface, the EBS volume ID is available via the controller serial number and the device name specified in EC2 API requests is provided by an NVMe vendor extension to the Identify Controller command. This enables backward compatible symbolic links to be created by a utility script. For more information see the EC2 documentation on device naming and NVMe based EBS volumes.
Second, by default the NVMe drivers included in most operating systems implement an I/O timeout. If an I/O does not complete in an implementation specific amount of time, usually tens of seconds, the driver will attempt to cancel the I/O, retry it, or return an error to the component that issued the I/O. The Xen PV block device interface does not time out I/O, which can result in processes that cannot be terminated if it is waiting for I/O. The Linux NVMe driver behavior can be modified by specifying a higher value for the nvme.io timeout kernel module parameter.
Third, the NVMe interface can transfer much larger amounts of data per I/O, and in some cases may be able to support more outstanding I/O requests, compared to the Xen PV block interface. This can cause higher I/O latency if very large I/Os or a large number of I/O requests are issued to volumes designed to support throughput workloads like EBS Throughput Optimized HDD (st1) and Cold HDD (sc1) volumes. This I/O latency is normal for throughput optimized volumes in these scenarios, but may cause I/O timeouts in NVMe drivers. The I/O timeout can be adjusted in the Linux driver by specifying a larger value for the nvme_core.io_timeout kernel module parameter.
What networking capabilities are included in this feature?
Enhanced Networking
Amazon EC2 | Compute
We currently support enhanced networking capabilities using SR-IOV (Single Root I/O Virtualization). SR-IOV is a method of device virtualization that provides higher I/O performance and lower CPU utilization compared to traditional implementations. For supported Amazon EC2 instances, this feature provides higher packet per second (PPS) performance, lower inter-instance latencies, and very low network jitter.
Why should I use Enhanced Networking?
Enhanced Networking
Amazon EC2 | Compute
If your applications benefit from high packet-per-second performance and/or low latency networking, Enhanced Networking will provide significantly improved performance, consistence of performance and scalability.
How can I enable Enhanced Networking on supported instances?
Enhanced Networking
Amazon EC2 | Compute
In order to enable this feature, you must launch an HVM AMI with the appropriate drivers. M5, C5, H1, R4, X1, I3, P3, P2, G3, and m4.16xlarge instances provide the Elastic Network Adapter (ENA) interface (which uses the “ena” Linux driver) for Enhanced Networking. C3, C4, R3, I2, M4 (except m4.16xlarge) and D2 instances use Intel® 82599g Virtual Function Interface (which uses the “ixgbevf” Linux driver). Amazon Linux AMI includes both of these drivers by default. For AMIs that do not contain these drivers, you will need to download and install the appropriate drivers based on the instance types you plan to use. You can use Linux or Windows instructions to enable Enhanced Networking in AMIs that do not include the SR-IOV driver by default. Enhanced Networking is only supported in Amazon VPC.
Do I need to pay an additional fee to use Enhanced Networking?
Enhanced Networking
Amazon EC2 | Compute
No, there is no additional fee for Enhanced Networking. To take advantage of Enhanced Networking you need to launch the appropriate AMI on a supported instance type in a VPC.
Why is Enhanced Networking only supported in Amazon VPC?
Enhanced Networking
Amazon EC2 | Compute
Amazon VPC allows us to deliver many advanced networking features to you that are not possible in EC2-Classic. Enhanced Networking is another example of a capability enabled by Amazon VPC.
Which instance types support Enhanced Networking?
Enhanced Networking
Amazon EC2 | Compute
Currently C3, C4, C5, D2, I3, I2, H1, M5, M4, X1 and R3 instances support Enhanced Networking. X1, P2, P3, G3, I3, R4 and m4.16xlarge instances provide the Elastic Network Adapter (ENA) interface for Enhanced Networking. C3, C4, R3, I2, M4 (except m4.16xlarge) and D2 instances, use Intel® 82599 Virtual Function Interface.
