Scenarios

When optimizing a Linux private image, you need to install native Xen and KVM drivers on the ECS.

If you do not install the Xen driver, the ECS network performance will be poor, and the security groups and firewall configured for the ECS will not take effect.

If you do not install the KVM driver, NICs of the ECS may not be detected and the ECS cannot communicate with other resources. Therefore, you must install Xen and KVM drivers.

Prerequisites

• ECSs that use native Linux Xen and KVM drivers must have a kernel later than the 2.6.24 version.
• Disable your antivirus and intrusion detection software. You can enable the software after Xen and KVM drivers are installed.

CentOS, EulerOS

1. Run the following command to open the /etc/dracut.conf file:

   vi /etc/dracut.conf

2. Press i to enter editing mode and add the xen-pv and VirtIO drivers to add_drivers (the format depends on the OS requirements).

   [root@CTU10000xxxxx ~]# vi /etc/dracut.conf 
   # additional kernel modules to the default 
   add_drivers+="xen-blkfront xen-netfront virtio_blk virtio_scsi virtio_net virtio_pci virtio_ring virtio" 
   ......

3. Press Esc, enter :wq, and press Enter. The system saves the change and exits the /etc/dracut.conf file.
4. Run the following command to generate initrd again:

   dracut -f /boot/initramfs-2.6.32-573.8.1.el6.x86_64.img

   If the virtual file system is not the default initramfs, run the dracut -f Name of the initramfs or initrd file actually used command. The actual initramfs or initrd file name can be obtained from the GRUB configuration file, which can be /boot/grub/grub.cfg, /boot/gurb2/grub.cfg, or /boot/grub/grub.conf depending on the OS.

5. If the virtual file system is initramfs, run the following commands to check whether native Xen and KVM drivers have been loaded:

   lsinitrd /boot/initramfs-`uname -r`.img | grep xen

   lsinitrd /boot/initramfs-`uname -r`.img | grep virtio

   If the virtual file system is initrd, run the following commands to check whether native Xen and KVM drivers have been loaded:

   lsinitrd /boot/initrd-`uname -r` | grep xen

   lsinitrd /boot/initrd-`uname -r` | grep virtio

   If the virtual file system is initramfs, the following information is displayed:

   [root@CTU10000xxxxx home]# lsinitrd /boot/initramfs-`uname -r`.img | grep xen 
   -rwxr--r--   1 root     root        54888 Jul 16 17:53 lib/modules/2.6.32-573.8.1.el6.x86_64/kernel/drivers/block/xen-blkfront.ko 
   -rwxr--r--   1 root     root        45664 Jul 16 17:53 lib/modules/2.6.32-573.8.1.el6.x86_64/kernel/drivers/net/xen-netfront.ko 
    
   [root@CTU10000xxxxx home]# lsinitrd /boot/initramfs-`uname -r`.img | grep virtio 
   -rwxr--r--   1 root     root        23448 Jul 16 17:53 lib/modules/2.6.32-573.8.1.el6.x86_64/kernel/drivers/block/virtio_blk.ko 
   -rwxr--r--   1 root     root        50704 Jul 16 17:53 lib/modules/2.6.32-573.8.1.el6.x86_64/kernel/drivers/net/virtio_net.ko 
   -rwxr--r--   1 root     root        28424 Jul 16 17:53 lib/modules/2.6.32-573.8.1.el6.x86_64/kernel/drivers/scsi/virtio_scsi.ko 
   drwxr-xr-x   2 root     root            0 Jul 16 17:53 lib/modules/2.6.32-573.8.1.el6.x86_64/kernel/drivers/virtio 
   -rwxr--r--   1 root     root        14544 Jul 16 17:53 lib/modules/2.6.32-573.8.1.el6.x86_64/kernel/drivers/virtio/virtio.ko 
   -rwxr--r--   1 root     root        21040 Jul 16 17:53 lib/modules/2.6.32-573.8.1.el6.x86_64/kernel/drivers/virtio/virtio_pci.ko 
   -rwxr--r--   1 root     root        18016 Jul 16 17:53 lib/modules/2.6.32-573.8.1.el6.x86_64/kernel/drivers/virtio/virtio_ring.ko

   

   If you add built-in drivers to the initrd or initramfs file, the ECS will not be affected. This makes it easy to modify the drivers. However, you cannot check the drivers by running the lsinitrd command. You can run the following commands to check whether the drivers are built-in ones in the kernel:

   cat /boot/config-`uname -r` | grep CONFIG_VIRTIO | grep y

   cat /boot/config-`uname -r` | grep CONFIG_XEN | grep y

Ubuntu and Debian

1. Run the following command to open the modules file:

   vi /etc/initramfs-tools/modules

2. Press i to enter editing mode and add the xen-pv and VirtIO drivers to the /etc/initramfs-tools/modules file (the format depends on the OS requirements).

   [root@CTU10000xxxxx ~]#vi /etc/initramfs-tools/modules 
   ......
   # Examples: 
   # 
   # raid1 
   # sd_mOd 
   xen-blkfront
   xen-netfront
   virtio_blk
   virtio_scsi
   virtio_net
   virtio_pci
   virtio_ring
   virtio

3. Press Esc, enter :wq, and press Enter. The system saves the change and exits the /etc/initramfs-tools/modules file.
4. Run the following command to generate initrd again:

   update-initramfs -u

5. Run the following commands to check whether native Xen and KVM drivers have been installed:

   lsinitramfs /boot/initrd.img-`uname -r` |grep xen

   lsinitramfs /boot/initrd.img-`uname -r` |grep virtio

   [root@ CTU10000xxxxx home]# lsinitramfs /boot/initrd.img-`uname -r` |grep xen 
   lib/modules/3.5.0-23-generic/kernel/drivers/net/ethernet/qlogic/netxen 
   lib/modules/3.5.0-23-generic/kernel/drivers/net/ethernet/qlogic/netxen/netxen_nic.ko 
   lib/modules/3.5.0-23-generic/kernel/drivers/net/xen-netback 
   lib/modules/3.5.0-23-generic/kernel/drivers/net/xen-netback/xen-netback.ko 
   lib/modules/3.5.0-23-generic/kernel/drivers/block/xen-blkback 
   lib/modules/3.5.0-23-generic/kernel/drivers/block/xen-blkback/xen-blkback.ko 
    
   [root@ CTU10000xxxxx home]# lsinitramfs /boot/initrd.img-`uname -r` |grep virtio 
   lib/modules/3.5.0-23-generic/kernel/drivers/scsi/virtio_scsi.ko

   

   If you add built-in drivers to the initrd or initramfs file, the ECS will not be affected. This makes it easy to modify the drivers. However, you cannot check the drivers by running the lsinitrd command. You can run the following commands to check whether the drivers are built-in ones in the kernel:

   [root@ CTU10000xxxxx home]# cat /boot/config-`uname -r` | grep CONFIG_VIRTIO | grep y
   CONFIG_VIRTIO_BLK=y
   CONFIG_VIRTIO_NET=y
   CONFIG_VIRTIO=y
   CONFIG_VIRTIO_RING=y
   CONFIG_VIRTIO_PCI=y
   CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES=y
   [root@ CTU10000xxxxx home]# cat /boot/config-`uname -r` | grep CONFIG_XEN | grep y
   CONFIG_XEN_BLKDEV_FRONTEND=y
   CONFIG_XEN_NETDEV_FRONTEND=y

SUSE and openSUSE

If the OS version is earlier than SUSE 12 SP1 or openSUSE 13, modify the /etc/sysconfig/kernel file. For details, see scenario 1.

If the OS version is SUSE 12 SP1, modify the /etc/dracut.conf file and add xen-pv and VirtIO drivers. For details, see scenario 2.