Managing Regions

A region is a grouping of one or more NVDIMMs, or an interleaved set, that can be divided up into one or more Namespaces. Regions are of type PMEM or BLK. See PMEM or BLK modes for more information. Regions can only be created, destroyed, and configured using the vendor specific NVDIMM utility that manages the NVDIMMs or BIOS options, if available.

Listing Regions

Currently available regions can be shown using the -R or --regions flag to the ndctl list command, eg:

# ndctl list --regions
[
  {
    "dev":"region1",
    "size":1623497637888,
    "align":100663296,
    "available_size":1623497637888,
    "max_available_extent":1623497637888,
    "type":"pmem",
    "iset_id":-2506113243053544244,
    "persistence_domain":"memory_controller"
  },
  {
    "dev":"region0",
    "size":1623497637888,
    "align":100663296,
    "available_size":1623497637888,
    "max_available_extent":1623497637888,
    "type":"pmem",
    "iset_id":3259620181632232652,
    "persistence_domain":"memory_controller"
  }
]

Filtering (Searching) the output

The output can be filtered on any filter supported by ndctl list, ie --bus, --region, --dimm, --namespace, --type, and --numa-node. For example:

// Show only 'region0'
# ndctl list --region region0

// Show the region used by NVDIMM 'nmem0'
# ndctl list --dimm nmem0 --regions

// Show the region used by 'namespace0.0'
# ndctl list --namespace namespace0.0 --regions

Listing Disabled Regions

Disabled regions can be included in the show output using the -Ri or --regions --idle flags, eg:

# ndctl list --regions --idle
[
  {
    "dev":"region1",
    "size":1623497637888,
    "align":100663296,
    "available_size":1623497637888,
    "max_available_extent":1623497637888,
    "type":"pmem",
    "iset_id":-2506113243053544244,
    "persistence_domain":"memory_controller"
  },
  {
    "dev":"region0",
    "size":1623497637888,
    "align":100663296,
    "available_size":1623497637888,
    "max_available_extent":1623497637888,
    "type":"pmem",
    "iset_id":3259620181632232652,
    "state":"disabled",     <----
    "persistence_domain":"memory_controller"
  }
]

Disabling Regions

1) List all active/enabled regions:

# ndctl list -R
[
  {
    "dev":"region1",
    "size":1623497637888,
    "align":100663296,
    "available_size":1623497637888,
    "max_available_extent":1623497637888,
    "type":"pmem",
    "iset_id":-2506113243053544244,
    "persistence_domain":"memory_controller"
  },
  {
    "dev":"region0",
    "size":1623497637888,
    "align":100663296,
    "available_size":1623497637888,
    "max_available_extent":1623497637888,
    "type":"pmem",
    "iset_id":3259620181632232652,
    "persistence_domain":"memory_controller"
  }
]

A filtered list of active/enabled regions can be displayed using the -r <region-id> or --region <region-id> option, eg:

# ndctl list -R -r region0
- or -
# ndctl list -R -region region0

2) Disable the region

# ndctl disable-region region0
disabled 1 region

3) Verify the region is disabled by including the -i option:

# ndctl list -Ri
[
  ...
  {
    "dev":"region0",
    "size":1623497637888,
    "align":100663296,
    "available_size":1623497637888,
    "max_available_extent":1623497637888,
    "type":"pmem",
    "iset_id":3259620181632232652,
    "state":"disabled",     <---
    "persistence_domain":"memory_controller"
  }
]

Enabling Regions

1) List disabled/inactive regions

# ndctl list -Ri
[
  ...
  {
    "dev":"region0",
    "size":1623497637888,
    "align":100663296,
    "available_size":1623497637888,
    "max_available_extent":1623497637888,
    "type":"pmem",
    "iset_id":3259620181632232652,
    "state":"disabled",     <---
    "persistence_domain":"memory_controller"
  }
]

A filtered list of active/enabled regions can be displayed using the -r <region-id> or --region <region-id> option, eg:

# ndctl list -R -r region0
- or -
# ndctl list -R -region region0

2) Enable the region

# ndctl enable-region region0
enabled 1 region

3) Verify the region is enabled using ndctl list -R. Note the 'state' field is not displayed for enabled regions.

# ndctl list -R
[
  {
    "dev":"region1",
    "size":1623497637888,
    "align":100663296,
    "available_size":1623497637888,
    "max_available_extent":1623497637888,
    "type":"pmem",
    "iset_id":-2506113243053544244,
    "persistence_domain":"memory_controller"
  },
  {
    "dev":"region0",
    "size":1623497637888,
    "align":100663296,
    "available_size":1623497637888,
    "max_available_extent":1623497637888,
    "type":"pmem",
    "iset_id":3259620181632232652,
    "persistence_domain":"memory_controller"
  }
]