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Problem
We need the ability to prepare a subset of storage controller managed pageservers for decommisioning. The storage controller cannot currently express this in terms of scheduling constraints (it's a pretty special case, so I'm not sure it even should).
Summary of Changes
A new
drain
command is added tostorcon_cli
. It takes a set of nodes to drain and migrates primary attachments outside of said set. Simple round robing assignment is used under the assumption that nodes outside of the draining set are evenly balanced.Note that secondary locations are not migrated. This is fine for staging, but the migration API will have to be extended for prod in order to allow migration of secondaries as well.
I've tested this out against a neon local cluster. The immediate use for this command will be to migrate staging to ARM(Arch64) pageservers.
Related https://github.com/neondatabase/cloud/issues/14029
Checklist before requesting a review
Checklist before merging