Configure a MOM Node Like a Login Node

The MOM node is not an SDB node.

If this site has MOM (machine-oriented miniserver) nodes that are not also SDB nodes, Cray recommends treating them the same as login nodes so that they will have the same capabilities. This means that they should be assigned the same NIMS group, boot image, node group, and so forth.

If this site chooses to use a custom image for MOM nodes instead of the login image, then modify the steps of this procedure to add MOM nodes to a MOM-specific node group, and update the NIMS map to assign those nodes a custom NIMS group, custom image, and the appropriate netroot kernel parameter. To create a custom recipe (preferrably one that has the login recipe as a subrecipe) and image, see Install Third-Party Software with a Custom Image Recipe.

Configure cray_node_groups to add the MOM node to a login node group.
Depending on the architecture (x86-64 or AArch64) of the MOM node, use one of the following sets of commands to check the members of the login node group and add the MOM node to that group, as needed.
The example commands use c0-1c1s3n0 as the MOM node and p0 as the CLE config set. Substitute the correct cname and CLE config set for this system.
For an x86-64 MOM node:
```
smw# cfgset get cray_node_groups.settings.groups.data.login_nodes_x86_64.members p0

smw# cfgset modify --add c0-1c1s3n0 \
cray_node_groups.settings.groups.data.login_nodes_x86_64.members p0
```
For an AArch64 MOM node:
```
smw# cfgset get cray_node_groups.settings.groups.data.login_nodes_aarch64.members p0

smw# cfgset modify --add c0-1c1s3n0 \
cray_node_groups.settings.groups.data.login_nodes_aarch64.members p0
```
Update and validate the CLE config set.
Substitute the correct CLE config set for this system.
```
smw# cfgset update p0
smw# cfgset validate p0
```
Assign the MOM node to the login NIMS group.
This will ensure that the MOM node is booted with the login boot image. This example uses c0-1c1s3n0 as the MOM node. Substitute the correct cname for this system.
Remove from the service NIMS group and add to the login NIMS group:
```
smw# cnode update -G service -g login c0-1c1s3n0
```
Assign the login boot image to the MOM node.
1. Determine which boot image is being used for login nodes on this system.
  This example uses c0-0c0s2n2 as the login node. Substitute the correct cname for this system.
```
smw# cnode list c0-0c0s2n2
```
2. Choose a login image and assign it as the boot image for the MOM node.
  If using a netroot login image, assign the initrd image as the boot image.
  This example uses c0-1c1s3n0 as the MOM node and the netroot initrd image for an x86-64 login node. Substitute the correct cname and image for this system.
```
smw# cnode update -i initrd-login-large_cle_6.0.up02_sles_12sp3-x86_64 c0-1c1s3n0
```
3. Set the netroot kernel parameter.
  If using a netroot login image, assign the other image of the pair of netroot images (the one without "initrd" in the name) to the netroot kernel parameter.
  This example uses c0-1c1s3n0 as the MOM node and the netroot image for an x86-64 login node. Substitute the correct cname and image for this system.
```
smw# cnode update -s netroot=login-large_cle_6.0.up02_sles_12sp3-x86_64 c0-1c1s3n0
```
  If using a tmpfs image, the netroot kernel parameter may need to be removed from the NIMS map for the MOM node. If so, use the following command.
```
smw# cnode update -K netroot c0-1c1s3n0
```
Confirm that the NIMS group, boot image, and netroot parameter are correct for the MOM node.
Substitute the correct MOM node cname for this system.
```
smw# cnode list c0-1c1s3n0
```

Reboot the MOM node.

Substitute the correct MOM node cname for this system.

smw# su - crayadm
crayadm@smw> xtcli halt c0-1c1s3n0
crayadm@smw> xtbootsys --reboot -r "rebooting MOM node with login image" c0-1c1s3n0