Chapter 11. Configuring NVDIMM Compute nodes to provide persistent memory for instances

Procedure

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

2. Source the stackrc file:

   [stack@director ~]$ source ~/stackrc

3. Generate a new roles data file named roles_data_pmem.yaml that includes the Controller, Compute, and ComputePMEM roles:

   (undercloud)$ openstack overcloud roles \
    generate -o /home/stack/templates/roles_data_pmem.yaml \
    Compute:ComputePMEM Compute Controller

4. Open roles_data_pmem.yaml and edit or add the following parameters and sections:

   Expand

   Section/Parameter	Current value	New value
   Role comment	Role: Compute	Role: ComputePMEM
   Role name	name: Compute	name: ComputePMEM
   description	Basic Compute Node role	PMEM Compute Node role
   HostnameFormatDefault	%stackname%-novacompute-%index%	%stackname%-novacomputepmem-%index%
   deprecated_nic_config_name	compute.yaml	compute-pmem.yaml

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5. Register the NVDIMM Compute nodes for the overcloud by adding them to your node definition template, node.json or node.yaml. For more information, see Registering nodes for the overcloud in the Director Installation and Usage guide.

6. Inspect the node hardware:

   (undercloud)$ openstack overcloud node introspect --all-manageable --provide

   For more information, see Creating an inventory of the bare-metal node hardware in the Director Installation and Usage guide.

7. Create the compute-pmem overcloud flavor for PMEM Compute nodes:

   (undercloud)$ openstack flavor create --id auto \
    --ram <ram_size_mb> --disk <disk_size_gb> \
    --vcpus <no_vcpus> compute-pmem

   • Replace <ram_size_mb> with the RAM of the bare metal node, in MB.
   • Replace <disk_size_gb> with the size of the disk on the bare metal node, in GB.

   • Replace <no_vcpus> with the number of CPUs on the bare metal node.

     Note

     These properties are not used for scheduling instances. However, the Compute scheduler does use the disk size to determine the root partition size.

8. Retrieve a list of your nodes to identify their UUIDs:

   (undercloud)$ openstack baremetal node list

9. Tag each bare metal node that you want to designate for PMEM workloads with a custom PMEM resource class:

   (undercloud)$ openstack baremetal node set \
    --resource-class baremetal.PMEM <node>

   Replace <node> with the ID of the bare metal node.

10. Associate the compute-pmem flavor with the custom PMEM resource class:

    (undercloud)$ openstack flavor set \
     --property resources:CUSTOM_BAREMETAL_PMEM=1 \
      compute-pmem

    To determine the name of a custom resource class that corresponds to a resource class of a Bare Metal service node, convert the resource class to uppercase, replace all punctuation with an underscore, and prefix with CUSTOM_.

    Note

    A flavor can request only one instance of a bare metal resource class.

11. Set the following flavor properties to prevent the Compute scheduler from using the bare metal flavor properties to schedule instances:

    (undercloud)$ openstack flavor set \
     --property resources:VCPU=0 --property resources:MEMORY_MB=0 \
     --property resources:DISK_GB=0 compute-pmem

12. Add the following parameters to the node-info.yaml file to specify the number of PMEM Compute nodes, and the flavor to use for the PMEM-designated Compute nodes:

    parameter_defaults:
      OvercloudComputePMEMFlavor: compute-pmem
      ComputePMEMCount: 3 #set to the no of NVDIMM devices you have

13. To verify that the role was created, enter the following command:

    (undercloud)$ openstack overcloud profiles list

Procedure

1. Create a new Compute environment file for configuring NVDIMM Compute nodes, for example, env_pmem.yaml.

2. To partition the NVDIMM regions into PMEM namespaces that the instances can use, add the NovaPMEMNamespaces role-specific parameter to the PMEM role in your Compute environment file, and set the value using the following format:

   <size>:<namespace_name>[,<size>:<namespace_name>]

   Use the following suffixes to represent the size:

   • "k" or "K" for KiB
   • "m" or "M" for MiB
   • "G" or "G" for GiB

   • "t" or "T" for TiB

     For example, the following configuration creates four namespaces, three of size 6 GiB, and one of size 100 GiB:

     parameter_defaults:
       ComputePMEMParameters:
         NovaPMEMNamespaces: "6G:ns0,6G:ns1,6G:ns2,100G:ns3"

3. To map the PMEM namespaces to labels that can be used in a flavor, add the NovaPMEMMappings role-specific parameter to the PMEM role in your Compute environment file, and set the value using the following format:

   <label>:<namespace_name>[|<namespace_name>][,<label>:<namespace_name>[|<namespace_name>]].

   For example, the following configuration maps the three 6 GiB namespaces to the label "6GB", and the 100 GiB namespace to the label "LARGE":

   parameter_defaults:
     ComputePMEMParameters:
       NovaPMEMNamespaces: "6G:ns0,6G:ns1,6G:ns2,100G:ns3"
       NovaPMEMMappings: "6GB:ns0|ns1|ns2,LARGE:ns3"

4. Save the updates to your Compute environment file.

5. Add your Compute environment file to the stack with your other environment files and deploy the overcloud:

   (undercloud)$ openstack overcloud deploy --templates \
    -r /home/stack/templates/roles_data_pmem.yaml \
    -e /home/stack/templates/node-info.yaml \
    -e [your environment files] \
    -e /home/stack/templates/env_pmem.yaml

6. Create and configure the flavors that your cloud users can use to launch instances that have vPMEM. The following example creates a flavor that requests a small PMEM device, 6GB, as mapped in Step 3:

   (overcloud)$ openstack flavor create --vcpus 1 --ram 512 --disk 2  \
    --property hw:pmem='6GB' small_pmem_flavor

Verification

1. Create an instance using one of the PMEM flavors:

   (overcloud)$ openstack flavor list
   (overcloud)$ openstack server create --flavor small_pmem_flavor \
    --image rhel8 pmem_instance

2. Log in to the instance as a cloud user. For more information, see Connecting to an instance.

3. List all the disk devices attached to the instance:

   $ sudo fdisk -l /dev/pmem0

   The instance has vPMEM if one of the devices listed is NVDIMM.