RAID Configuration

RAID Configuration

Overview

Ironic supports RAID configuration for bare metal nodes. It allows operators to specify the desired RAID configuration via the OpenStackClient CLI or REST API. The desired RAID configuration is applied on the bare metal during manual cleaning.

The examples described here use the OpenStackClient CLI; please see the REST API reference for their corresponding REST API requests.

Prerequisites

The bare metal node needs to use a hardware type that supports RAID configuration. RAID interfaces may implement RAID configuration either in-band or out-of-band.

In-band RAID configuration is done using the Ironic Python Agent ramdisk. For in-band RAID configuration using agent ramdisk, a hardware manager which supports RAID should be bundled with the ramdisk. Whether a node supports RAID configuration could be found using the CLI command openstack baremetal node validate <node-uuid>.

Build agent ramdisk which supports RAID configuration

For doing in-band hardware RAID configuration, Ironic needs an agent ramdisk bundled with a hardware manager which supports RAID configuration for your hardware. For example, the DIB support for Proliant Hardware Manager should be used for HPE Proliant Servers.

Note

For in-band software RAID, the agent ramdisk does not need to be bundled with a hardware manager as the generic hardware manager in the Ironic Python Agent already provides (basic) support for software RAID.

RAID configuration JSON format

The desired RAID configuration and current RAID configuration are represented in JSON format.

Target RAID configuration

This is the desired RAID configuration on the bare metal node. Using the OpenStackClient CLI (or REST API), the operator sets target_raid_config field of the node. The target RAID configuration will be applied during manual cleaning.

Target RAID configuration is a dictionary having logical_disks as the key. The value for the logical_disks is a list of JSON dictionaries. It looks like:

{
 "logical_disks": [
                   {<desired properties of logical disk 1>},
                   {<desired properties of logical disk 2>},
                   .
                   .
                   .
                  ]
}

If the target_raid_config is an empty dictionary, it unsets the value of target_raid_config if the value was set with previous RAID configuration done on the node.

Each dictionary of logical disk contains the desired properties of logical disk supported by the hardware type. These properties are discoverable by:

openstack baremetal --os-baremetal-api-version 1.15 driver raid property list <driver name>

The RAID feature is available in ironic API version 1.15 and above. If --os-baremetal-api-version is not used in the CLI, it will error out with the following message:

  No API version was specified and the requested operation was not
  supported by the client's negotiated API version 1.9. Supported
  version range is: 1.1 to ...

where the "..." in above error message would be the maximum version
supported by the service.

The RAID properties can be split into 4 different types:

  1. Mandatory properties. These properties must be specified for each logical disk and have no default values.

    • size_gb - Size (Integer) of the logical disk to be created in GiB. MAX may be specified if the logical disk should use all of the remaining space available. This can be used only when backing physical disks are specified (see below).

    • raid_level - RAID level for the logical disk. Ironic supports the following RAID levels: 0, 1, 2, 5, 6, 1+0, 5+0, 6+0.

  2. Optional properties. These properties have default values and they may be overridden in the specification of any logical disk.

    • volume_name - Name of the volume. Should be unique within the Node. If not specified, volume name will be auto-generated.

    • is_root_volume - Set to true if this is the root volume. At most one logical disk can have this set to true; the other logical disks must have this set to false. The root device hint will be saved, if the RAID interface is capable of retrieving it. This is false by default.

  3. Backing physical disk hints. These hints are specified for each logical disk to let Ironic find the desired disks for RAID configuration. This is machine-independent information. This serves the use-case where the operator doesn’t want to provide individual details for each bare metal node.

    • share_physical_disks - Set to true if this logical disk can share physical disks with other logical disks. The default value is false.

    • disk_type - hdd or ssd. If this is not specified, disk type will not be a criterion to find backing physical disks.

    • interface_type - sata or scsi or sas. If this is not specified, interface type will not be a criterion to find backing physical disks.

    • number_of_physical_disks - Integer, number of disks to use for the logical disk. Defaults to minimum number of disks required for the particular RAID level.

  4. Backing physical disks. These are the actual machine-dependent information. This is suitable for environments where the operator wants to automate the selection of physical disks with a 3rd-party tool based on a wider range of attributes (eg. S.M.A.R.T. status, physical location). The values for these properties are hardware dependent.

    • controller - The name of the controller as read by the RAID interface. In order to trigger the setup of a Software RAID via the Ironic Python Agent, the value of this property needs to be set to software.

    • physical_disks - A list of physical disks to use as read by the RAID interface.

Note

If properties from both “Backing physical disk hints” or “Backing physical disks” are specified, they should be consistent with each other. If they are not consistent, then the RAID configuration will fail (because the appropriate backing physical disks could not be found).

Note

For software RAID as provided by the generic hardware manager that ships with the Ironic Python Agent, only the mandatory properties (plus the required controller property) are currently supported.

Examples for target_raid_config

Example 1. Single RAID disk of RAID level 5 with all of the space available. Make this the root volume to which Ironic deploys the image:

{
 "logical_disks": [
                   {
                    "size_gb": "MAX",
                    "raid_level": "5",
                    "is_root_volume": true
                   }
                  ]
}

Example 2. Two RAID disks. One with RAID level 5 of 100 GiB and make it root volume and use SSD. Another with RAID level 1 of 500 GiB and use HDD:

{
 "logical_disks": [
                   {
                    "size_gb": 100,
                    "raid_level": "5",
                    "is_root_volume": true,
                    "disk_type": "ssd"
                   },
                   {
                    "size_gb": 500,
                    "raid_level": "1",
                    "disk_type": "hdd"
                   }
                  ]
}

Example 3. Single RAID disk. I know which disks and controller to use:

{
 "logical_disks": [
                   {
                    "size_gb": 100,
                    "raid_level": "5",
                    "controller": "Smart Array P822 in Slot 3",
                    "physical_disks": ["6I:1:5", "6I:1:6", "6I:1:7"],
                    "is_root_volume": true
                   }
                  ]
}

Example 4. Using backing physical disks:

{
  "logical_disks":
    [
      {
        "size_gb": 50,
        "raid_level": "1+0",
        "controller": "RAID.Integrated.1-1",
        "volume_name": "root_volume",
        "is_root_volume": true,
        "physical_disks": [
                           "Disk.Bay.0:Encl.Int.0-1:RAID.Integrated.1-1",
                           "Disk.Bay.1:Encl.Int.0-1:RAID.Integrated.1-1"
                          ]
      },
      {
        "size_gb": 100,
        "raid_level": "5",
        "controller": "RAID.Integrated.1-1",
        "volume_name": "data_volume",
        "physical_disks": [
                           "Disk.Bay.2:Encl.Int.0-1:RAID.Integrated.1-1",
                           "Disk.Bay.3:Encl.Int.0-1:RAID.Integrated.1-1",
                           "Disk.Bay.4:Encl.Int.0-1:RAID.Integrated.1-1"
                          ]
      }
    ]
}

Example 5. Software RAID with two RAID devices:

{
 "logical_disks": [
                   {
                    "size_gb": 100,
                    "raid_level": "1",
                    "controller": "software"
                   },
                   {
                    "size_gb": "MAX",
                    "raid_level": "0",
                    "controller": "software"
                   }
                  ]
}

Current RAID configuration

After target RAID configuration is applied on the bare metal node, Ironic populates the current RAID configuration. This is populated in the raid_config field in the Ironic node. This contains the details about every logical disk after they were created on the bare metal node. It contains details like RAID controller used, the backing physical disks used, WWN of each logical disk, etc. It also contains information about each physical disk found on the bare metal node.

To get the current RAID configuration:

openstack baremetal --os-baremetal-api-version 1.15 node show <node-uuid-or-name>

Workflow

  • Operator configures the bare metal node with a hardware type that has a RAIDInterface other than no-raid. For instance, for Software RAID, this would be agent.

  • For in-band RAID configuration, operator builds an agent ramdisk which supports RAID configuration by bundling the hardware manager with the ramdisk. See Build agent ramdisk which supports RAID configuration for more information.

  • Operator prepares the desired target RAID configuration as mentioned in Target RAID configuration. The target RAID configuration is set on the Ironic node:

      openstack baremetal node set <node-uuid-or-name> \
         --target-raid-config <JSON file containing target RAID configuration>
    
    The CLI command can accept the input from standard input also:
       openstack baremetal node set <node-uuid-or-name> \
          --target-raid-config -
    
  • Create a JSON file with the RAID clean steps for manual cleaning. Add other clean steps as desired:

    [{
      "interface": "raid",
      "step": "delete_configuration"
    },
    {
      "interface": "raid",
      "step": "create_configuration"
    }]
    

    Note

    ‘create_configuration’ doesn’t remove existing disks. It is recommended to add ‘delete_configuration’ before ‘create_configuration’ to make sure that only the desired logical disks exist in the system after manual cleaning.

  • Bring the node to manageable state and do a clean action to start cleaning on the node:

    openstack baremetal node clean <node-uuid-or-name> \
       --clean-steps <JSON file containing clean steps created above>
    
  • After manual cleaning is complete, the current RAID configuration is reported in the raid_config field when running:

    openstack baremetal node show <node-uuid-or-name>
    

Limitations of Software RAID

There are certain limitations to be aware of when setting up a Software RAID via the Ironic Python Agent:

  • There is no way to select the disks which are used to set up the software RAID, so the Ironic Python Agent will use all available disks. This seems appropriate for servers with 2 or 4 disks, but needs to be considered when disk arrays are attached.

  • The number of created Software RAID devices must be 1 or 2. If there is only one Software RAID device, it has to be a RAID-1. If there are two, the first one has to be a RAID-1, while the RAID level for the second one can 0, 1, or 1+0. As the first RAID device will be the deployment device, enforcing a RAID-1 reduces the risk of ending up with a non-booting node in case of a disk failure.

  • There is no support for partition images, only whole-disk images are supported with Software RAID.

Using RAID in nova flavor for scheduling

The operator can specify the raid_level capability in nova flavor for node to be selected for scheduling:

nova flavor-key my-baremetal-flavor set capabilities:raid_level="1+0"

Developer documentation

In-band RAID configuration is done using IPA ramdisk. IPA ramdisk has support for pluggable hardware managers which can be used to extend the functionality offered by IPA ramdisk using stevedore plugins. For more information, see Ironic Python Agent Hardware Manager documentation.

The hardware manager that supports RAID configuration should do the following:

  1. Implement a method named create_configuration. This method creates the RAID configuration as given in target_raid_config. After successful RAID configuration, it returns the current RAID configuration information which ironic uses to set node.raid_config.

  2. Implement a method named delete_configuration. This method deletes all the RAID disks on the bare metal.

  3. Return these two clean steps in get_clean_steps method with priority as 0. Example:

    return [{'step': 'create_configuration',
             'interface': 'raid',
             'priority': 0},
            {'step': 'delete_configuration',
             'interface': 'raid',
             'priority': 0}]
    
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