Details
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Investigation
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Resolution: Done
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Major - P3
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None
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Not Needed
Description
The design document has more details about the changes which is being reviewed in WRITING-8015.
User-Facing Syntax Changes
Users will need to modify the change management scripts if they wish to opt-in into new mode
Users will need to make the startup script roll forward/back compatible
Users will need to write the script performing the roll forward/back procedure
API Changes
The internal SDAM protocol is likely to change. Will write SDAM tests, no spec changes required (do we have a document for internal SDAM extensions?).
We will avoid adding a new API version
Config File Changes
The new “catalogShard” option is added to the "sharding.clusterRole" section of the config file, “--catalogShard” command line option is added to the mongod.
Description of Linked Ticket
+underlined text+
Summary
We will make dedicated config servers optional for sharded clusters. Customers will have the option to designate a special shard that will hold both user data and config data. For one-shard clusters on Atlas, the shard will automatically be a special shard with both the shard role and config role.
Motivation
Eliminating dedicated config servers will reduce both the cost and the architectural complexity involved in single-shard sharded clusters. On Atlas, a single-shard M30 sharded cluster costs TWICE as much as an M30 replica set. This project would bring cost parity to single-shard clusters on Atlas and will make it easier for customers to start out with a sharded cluster or switch to a sharded cluster.
It also supports other use-cases:
- Serverless v2 - Serverless would like to remove the cost and complexity of dealing with config servers.
- Kubernetes - Some customers prefer to use a sharded cluster with a single shard because the mongos can act as a proxy. No config server would mean better resource utilization and less operational overhead
Cast of Characters
- Product Owner: garaudy.etienne
- Project Lead: lamont.nelson
- Program Manager: ratika.gandhi
- Drivers Contact:
Documentation
Product Description
Scope Document
Technical Design Document