AWS introduced 5th-generation EC2 instances in selected regions. These instances live on Nitro which is KVM based. These c5 and m5 instances are faster yet cheaper. The switch however cannot be done by a simple instance type change.
The following instructions apply to EL7
First, block devices switched to NVMe and their names changed to /dev/nvme0n1p1. If the AMI contains traditional block device names in /etc/fstab, they will be stuck at boot up. Use UUID or disk label solves the problem. Second, you may need ENA support enabled. Some of the 5th-generation instances uses 10Gbe NIC as the only option. Here is how I recently updated a CentOS AMI:
– launched a c4.large instance from existing AMI
– update kernel to the latest (yum update kernel)
– disable consistent network device naming (add biosdevname=0 net.ifnames=0 to /etc/sysconfig/grub)
– update grub config and regenerate initramfs images
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grub2-mkconfig > /boot/grub2/grub.cfg dracut --regenerate-all --force |
– stop instance
– enable ENA with awscli and start instances
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aws ec2 modify-instance-attribute --ena-support --instance-id i-xxx |
ENA support is included on kernel 3.2 and later, so there is no need to install it on EL7
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# modinfo ena filename: /lib/modules/3.10.0-693.2.2.el7.x86_64/kernel/drivers/net/ethernet/amazon/ena/ena.ko.xz version: 1.0.2 |
For EL6, the ena driver needs to be installed manually. Use DKMS to install the module, so the driver is automatically installed during future kernel upgrade.
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yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-6.noarch.rpm yum install git gcc kernel-devel-$(uname -r) dkms git clone https://github.com/amzn/amzn-drivers.git cp -ap amzn-drivers /usr/src/amzn-drivers-1.0.5 create file # /usr/src/amzn-drivers-1.0.5/dkms.conf PACKAGE_NAME="ena" PACKAGE_VERSION="1.0.5" CLEAN="make -C kernel/linux/ena clean" MAKE="make -C kernel/linux/ena/ BUILD_KERNEL=${kernelver}" BUILT_MODULE_NAME[0]="ena" BUILT_MODULE_LOCATION="kernel/linux/ena" DEST_MODULE_LOCATION[0]="/updates" DEST_MODULE_NAME[0]="ena" AUTOINSTALL="yes" dkms add -m amzn-drivers -v 1.0.5 dkms build -m amzn-drivers -v 1.0.5 dkms install -m amzn-drivers -v 1.0.5 modprobe ena dracut -f poweroff (next step requires instance be stopped) aws --region us-east-1 ec2 modify-instance-attribute --ena-support --instance-id i-xxx start instance in m5 or c5 [root@ip-172-17-0-101 ~]# ethtool -i eth0 driver: ena version: 1.5.0g firmware-version: bus-info: 0000:00:05.0 supports-statistics: yes supports-test: no supports-eeprom-access: no supports-register-dump: no supports-priv-flags: no [root@ip-172-17-0-101 ~]# curl http://169.254.169.254/2016-09-02/meta-data/instance-type c5.large |
References:
- https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/enhanced-networking-ena.html#enhanced-networking-ena-ubuntu
