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Enable or Disable Changed Block Tracking for OpenStack

You can monitor the changes that occur on virtual disks by enabling Changed Block Tracking (CBT) for your backups.

Before You Begin

  • For multi-tenant environments, to perform CBT-enabled backups within a project, you must have the Admin role in that project. For more information, see Multi-Tenant Deployments.
  • You can only enable CBT for VMs associated with a compute node where the cvcompute-svc package is installed. If there are multiple compute nodes and controller nodes in your environment, then you must install the cvcompute-svc package on each of the compute nodes and the cvcompute-api package on each of the controller nodes.

    To install the packages:

    1. Go to the Base folder.
    2. Copy the cvcompute-api tar.gz file to all the controller nodes, and then copy the cvcompute-svc tar.gz file to all the compute nodes.
    3. From each controller node, decompress the cvcompute-api tar.gz file. Follow the README instructions to install the package.

      By default, the plug-in only logs errors. This can be changed to log at a debug level by setting log_level=10 in the appropriate section of /etc/cvcompute/cvcompute.conf.

    4. From each compute node, decompress the cvcompute-svc tar.gz file. Follow the README instructions to install the package.
  • On the compute nodes, install the following tools:
    • Quick EMUlator (QEMU) Hypervisor Version 2.4 or later
    • virsh, that comes with the libvirt-client RPM package.
    • qemu-img, that you can install with qemu-img-rhev on RHEL and qemu-img-ev or qemu-img on CentOS.

Staging Area Requirements

  • The staging area is used to temporarily hold the changed extents of cinder volumes and other data. For optimal performance, verify that there is a local disk on each compute node for the staging area. You can attach an SSD class disk to the compute node to improve the performance further.
  • The size of the staging area can be determined by the size of the disks attached to the VMs (which are being backed-up) running on that particular compute node. If the environment is more I/O intensive, then set the size of the staging area as the total size of all the disks. Otherwise, 50% of the total size would be sufficient.
  • The staging area space is only required for the number of VMs that will be protected in parallel.

CAUTION Mount the staging area on an expandable volume, such as a Logical Volume Manager (LVM) so that you can resize the area, if necessary. If you mount the staging area on a fixed size volume, moving the staging area location may be required to accommodate an increase in data. When you move the staging area to a different location, the map of all previously changed extents is lost, which could also lead to a loss of data.

Procedures

Enable Changed Block Tracking for OpenStack

  1. From the CommCell Browser, expand Client Computers > virtualization_client > Virtual Server > OpenStack > backup set.
  2. Right-click the subclient, and then select Properties.

    The Subclient Properties dialog box appears.

  3. On the Backup Options tab, select the Use Changed Block Tracking check box, and then click OK.

Disable Changed Block Tracking for OpenStack

  1. From the CommCell Browser, expand Client Computers > virtualization_client > Virtual Server > OpenStack > backup set.
  2. Right-click the subclient, and then select Properties.

    The Subclient Properties dialog box appears.

  3. On the Backup Options tab, clear the Use Changed Block Tracking check box, and then click OK.
  4. Uninstall the CBT package.

    For each controller node:

    1. Stop cvcompute-api service, and remove references:

      # systemctl stop cvcompute-api
      # systemctl disable cvcompute-api
      # openstack endpoint delete <ID> #replace <ID> with the endpoint ID for cvcompute
      # openstack service delete <ID> #replace <ID> with the service ID for cvcompute

    2. Remove the associated files. As part of the installation, the option '--record api_files' saves a list of all files copied to the system (which can be found at: /etc/cvcompute/cvcompute_api_files.txt). These files can be manually removed to uninstall the cvcompute-api service.

    For each compute node:

    1. Stop the cvcompute-svc service, and remove the references:

      # systemctl stop cvcompute-svc
      # systemctl disable cvcompute-svc
      # semanage fcontext -d <staging dir>"(/.*)?" For example: semanage fcontext -d /home/qemubackup"(/.*)?"

    2. Remove the associated files. As part of the installation, the option '--record svc_files' saves a list of all files copied to the system (which can be found at: /etc/cvcompute/cvcompute_svc_files.txt). These files can be manually removed to uninstall the cvcompute-svc service.

Last modified: 12/3/2020 8:42:12 PM