Let a set of rabbit nodes be used as the "external" MGS nodes.

[roehrich-hpe]

In discussion with @jameshcorbett and @bdevcich-hpe 6/27/23: James requested that he be able to setup a specified number of rabbits as MGS nodes, and then that Flux be able to pick from those MGS's when it's creating a new Lustre filesystem. We suggested that he create a collection of persistentdw's to create the MGS's. Then let Flux specify one of those MGS's via the Servers resource. Then we'd substitute that into the pinned NnfStorageProfile as its externalMgs.

[roehrich-hpe]

Further request: Add a keyword to the persistentdw DW line that marks it as belonging to this collection of MGS nodes, and put them in a list in some Rabbit resource so Flux can look there for the complete list, and Rabbit can maintain the list when it is asked to destroy a persistentdw.

[roehrich-hpe]

Matt, Blake, Dean discussion from July 6:

The NNF software:

• Modify NNF software to allow a persistent filesystem to be created that is only an MGT.
• Create a system NnfStorageProfile specifically for these persistent filesystems that are being used to make an MGS of certain rabbits.
• Pinned storage profiles that are created for these MGT filesystems will have a label marking them as such, so the NNF software can query them and select from them.
• NnfStorageProfiles would allow a keyword for the value of the field where one would specify an externalMGS. The NNF software will substitute one of the NNF MGS nodes in place of that keyword when creating a pinned version of that profile. When used this way, the externalMGS field is allowed to contain only that single keyword; comma- and colon-separated items are not allowed.
• The NnfStorageProfile externalMGS field does not lose the ability to be used the way we use it today, to contain a NID list for an MGS that is external to the rabbits.

The Adminstrator:

• Create one workflow for each rabbit MGS that is being created. One workflow per persistent filesystem.
• System NnfStorageProfiles that are supposed to use these rabbit MGS nodes must be updated to specify an externalMGS with the new keyword.

Flux:

• Flux does not need to specify, for each job, which rabbit MGS it should use. The Rabbit software knows the list of available rabbit MGSs and will pick one of them.

The User:

• Create a job with a DW line that specifies one of the NnfStorageProfiles that have been adjusted by the Administrator to use these rabbit MGS nodes.

[jameshcorbett]

This sounds very promising, thanks. I'll discuss with my team lead.

[matthew-richerson]

This change was included in nnf-deploy release v0.0.4