Image guide

This guideline will describe the requirements, steps to make images, configurations about the image that can be used in z/VM solution.

Image Requirements

  • supported Linux distribution (for deploy). The following are supported: RHEL 6.2, 6.3, 6.4, 6.5, 6.6, and 6.7 RHEL 7.0, 7.1 and 7.2 SLES 11.2, 11.3, and 11.4 SLES 12 and SLES 12.1 Ubuntu 16.04
  • A supported root disk type for snapshot/spawn. The following are supported: FBA ECKD
  • Images created with the previous version of the OpenStack support should be recaptured with an updated zvmguestconfigure installed
  • An image deployed on a compute node must match the disk type supported by that compute node, as configured by the zvm_diskpool_type property in the zvmsdk.conf configuration file. A compute node supports deployment on either an ECKD or FBA image, but not both at the same time. If you wish to switch image types, you need to change the zvm_diskpool_type and zvm_diskpool properties in the zvmsdk.conf file, accordingly. Then restart the nova-compute service to make the changes take effect.
  • If you deploy an instance with an ephemeral disk, both the root disk and the ephemeral disk will be created with the disk type that was specified by zvm_diskpool_type property in the zvmsdk.conf file. That property can specify either ECKD or FBA.
  • The network interfaces must be IPv4 interfaces.
  • Image names should be restricted to the UTF-8 subset, which corresponds to the ASCII character set. In addition, special characters such as /, , $, %, @ should not be used. For the FBA disk type “vm”, capture and deploy is supported only for an FBA disk with a single partition. Capture and deploy is not supported for the FBA disk type “vm” on a CMS formatted FBA disk.
  • The virtual server/Linux instance used as the source of the new image should meet the following criteria: 1. The root filesystem must not be on a logical volume.
    1. The minidisk on which the root filesystem resides should be a minidisk of the same type as desired for a subsequent deploy (for example, an ECKD disk image should be captured for a subsequent deploy to an ECKD disk).
    2. not be a full-pack minidisk, since cylinder 0 on full-pack minidisks is reserved, and be defined with virtual address 0100.
    3. The root disk should have a single partition.
    4. The image being captured should not have any network interface cards (NICs) defined below virtual address 1100.

In addition to the specified criteria, the following recommendations allow for efficient use of the image:

  • The minidisk on which the root filesystem resides should be defined as a multiple of full gigabytes in size (for example, 1GB or 2GB). OpenStack specifies disk sizes in full gigabyte values, whereas z/VM handles disk sizes in other ways (cylinders for ECKD disks, blocks for FBA disks, and so on). See the appropriate online information if you need to convert cylinders or blocks to gigabytes; for example: http://www.mvsforums.com/helpboards/viewtopic.php?t=8316.
  • During subsequent deploys of the image, the OpenStack code will ensure that a disk image is not copied to a disk smaller than the source disk, as this would result in loss of data. The disk specified in the flavor should therefore be equal to or slightly larger than the source virtual machine’s root disk. IBM recommends specifying the disk size as 0 in the flavor, which will cause the virtual machine to be created with the same disk size as the source disk.