Chapter 6. Booting from cinder volumes

Procedure

1. Log in to the undercloud as the stack user.

2. Source the overcloud credentials:

   $ source ~/overcloudrc

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3. Set the iscsi_boot capability to true and the storage-interface to cinder for the selected node:

   $ openstack baremetal node set --property capabilities=iscsi_boot:true --storage-interface cinder <NODEID>

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   Replace `<NODEID> with the ID of the chosen node.

4. Create an iSCSI connector for the node:

   $ openstack baremetal volume connector create --node <NODEID> --type iqn --connector-id iqn.2010-10.org.openstack.node<NUM>

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   The connector ID for each node must be unique. In the example, the connector is iqn.2010-10.org.openstack.node<NUM> where <NUM> is an incremented number for each node.

Prerequisites

1. Download a Red Hat Enterprise Linux QCOW2 image and copy it to the /home/stack/ directory on the undercloud. You can download Red Hat Enterprise Linux KVM images in QCOW2 format from the following pages:

   • Red Hat Enterprise Linux 7
   • Red Hat Enterprise Linux 8

Procedure

1. Log in to the undercloud as the stack user.

2. Mount the QCOW2 image and access it as the root user:

   1. Load the nbd kernel module:

      $ sudo modprobe nbd

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   2. Connect the QCOW image as /dev/nbd0:

      $ sudo qemu-nbd --connect=/dev/nbd0 <IMAGE>

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   3. Check the partitions on the NBD:

      $ sudo fdisk /dev/nbd0 -l

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      New Red Hat Enterprise Linux QCOW2 images contain only one partition, which is usually named /dev/nbd0p1 on the NBD.

   4. Create a mount point for the image:

      mkdir /tmp/mountpoint

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   5. Mount the image:

      sudo mount /dev/nbd0p1 /tmp/mountpoint/

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   6. Mount your dev directory so that the image has access to device information on the host:

      sudo mount -o bind /dev /tmp/mountpoint/dev

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   7. Change the root directory to the mount point:

      sudo chroot /tmp/mountpoint /bin/bash

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3. Configure iSCSI on the image:

   Note

   Some commands in this step might report the following error:

   lscpu: cannot open /proc/cpuinfo: No such file or directory

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   This error is not critical and you can ignore the error.

   1. Move the resolv.conf file to a temporary location:

      # mv /etc/resolv.conf /etc/resolv.conf.bak

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   2. Create a temporary resolv.conf file to resolve DNS requests for the Red Hat Content Delivery Network. This example uses 8.8.8.8 for the nameserver:

      # echo "nameserver 8.8.8.8" > /etc/resolv.conf

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   3. Register the mounted image to the Red Hat Content Delivery Network:

      # subscription-manager register

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      Enter your username and password when the command prompts you.

   4. Attach a subscription that contains Red Hat Enterprise Linux:

      # subscription-manager list --all --available
      # subscription-manager attach --pool <POOLID>

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      Substitute <POOLID> with the pool ID of the subscription.

   5. Disable the default repositories:

      # subscription-manager repos --disable "*"

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   6. Enable the Red Hat Enterprise Linux repository:

      • Red Hat Enterprise Linux 7:

        # subscription-manager repos --enable "rhel-7-server-rpms"

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      • Red Hat Enterprise Linux 8:

        # subscription-manager repos --enable "rhel-8-for-x86_64-baseos-eus-rpms"

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   7. Install the iscsi-initiator-utils package:

      # yum install -y iscsi-initiator-utils

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   8. Unregister the mounted image:

      # subscription-manager unregister

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   9. Restore the original resolv.conf file:

      # mv /etc/resolv.conf.bak /etc/resolv.conf

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   10. Check the kernel version on the mounted image:

       # rpm -qa kernel

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       For example, if the output is kernel-3.10.0-1062.el7.x86_64, the kernel version is 3.10.0-1062.el7.x86_64. Note this kernel version for the next step.

       Note

       New Red Hat Enterprise Linux QCOW2 image have only one kernel version installed. If more than one kernel version is installed, use the latest one.

   11. Add the network and iscsi dracut modules to the initramfs image:

       # dracut --force --add "network iscsi" /boot/initramfs-<KERNELVERSION>.img <KERNELVERSION>

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       Replace <KERNELVERSION> with the version you obtained from rpm -qa kernel. The following example uses 3.10.0-1062.el7.x86_64 as the kernel version:

       # dracut --force --add "network iscsi" /boot/initramfs-3.10.0-1062.el7.x86_64.img 3.10.0-1062.el7.x86_64

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   12. Edit the /etc/default/grub configuration file and add rd.iscsi.firmware=1 to the GRUB_CMDLINE_LINUX parameter:

       # vi /etc/default/grub

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       The following example shows the GRUB_CMDLINE_LINUX parameter with the added rd.iscsi.firmware=1 kernel argument:

       GRUB_CMDLINE_LINUX="console=tty0 crashkernel=auto console=ttyS0,115200n8 no_timer_check net.ifnames=0 rd.iscsi.firmware=1"

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       Save these changes.

       Note

       Do not rebuild the grub menu configuration at this step. A later step in this procedure rebuilds the grub menu as a temporary virtual machine.

   13. Exit from the mounted image back to your host operating system:

       # exit

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4. Unmount the image:

   1. Unmount the dev directory from the temporary mount point:

      $ sudo umount /tmp/mountpoint/dev

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   2. Unmount the image from the mount point:

      $ sudo umount /tmp/mountpoint

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   3. Disconnect the QCOW2 image from /dev/nbd0/:

      $ sudo qemu-nbd --disconnect /dev/nbd0

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5. Rebuild the grub menu configuration on the image:

   1. Install the libguestfs-tools package:

      $ sudo yum -y install libguestfs-tools

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      Important

      If you install the libguestfs-tools package on the undercloud, disable iscsid.socket to avoid port conflicts with the tripleo_iscsid service on the undercloud:

      $ sudo systemctl disable --now iscsid.socket

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   2. Set the libguestfs backend to use QEMU directly:

      $ export LIBGUESTFS_BACKEND=direct

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   3. Update the grub configuration on the image:

      $ guestfish -a <IMAGE> -m /dev/sda1 sh "/sbin/grub2-mkconfig -o /boot/grub2/grub.cfg"

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Procedure

1. Log in to the undercloud as the stack user.

2. Upload the iSCSI-enabled image to glance:

   $ openstack image create --disk-format qcow2 --container-format bare --file rhel-server-7.7-x86_64-kvm.qcow2 rhel-server-7.7-iscsi

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3. Create a volume from the image:

   $ openstack volume create --size 10 --image rhel-server-7.7-iscsi --bootable rhel-test-volume

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4. Create a bare metal instance that uses the boot volume in cinder:

   $ openstack server create --flavor baremetal --volume rhel-test-volume --key default rhel-test

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