Documentation Request Summary:

The new startup parameter should be documented.

Description

Added new startup parameter

--setParameter skipShardingConfigurationChecks=true

Only for use when starting a shard or config server as a standalone for maintenance ops.

Scope of changes (files that need work and how much)

• parameter
• Add ref to shardsvr and configsvr 

• 3.2/3.4 - Change Oplog Size (S)

• 3.2/3.4/3.6 - Rolling Index Upgrades (S)

• 3.2/3.4/3.6 - Perform Maintenance on Replica Set Members (S)

Note: Some confusion between this and HELP-6145, which implies this flag might only be required for 3.2. Need to test this for each MongoDB version and see what happens.

Impact to other docs outside of this product

N/A

MVP (work and date?)

• Update 3.2 docs (0.25)
• Update 3.4 docs (0.1)
• Update 3.6 docs (0.1)

Since this would break the aforementioned tutorials, suggest setting as P2 and resolving by first week of April.

Resources (e.g. Scope Docs, Invision)

N/A

Engineering Ticket Description:

Starting with MongoDB version 3.2, all sharding database components (config server and shard replica sets) persist the fact that they belong to a sharded cluster. This information is stored in two places - the cluster identity document and the replica set configuration (config servers only).

Once this information persisted, it is not possible to restart a config server or shard as an independent replica set, because startup will fail if -configsvr or -shardsvr are missing. This serves as a protection against customers inadvertently omitting startup parameters and misconfiguring their systems, but it also prevents the shard to be started up for maintenance (e.g., restore).

In order to unify the non-cluster behaviour across all versions and unblock the Cloud team, on all versions starting from 3.2 we will introduce a new startup-only parameter on mongod called --setParameter skipShardingConfigurationChecks=true, which is incompatible with --configsvr or --shardsvr. The meaning of this flag is "I am planning to restore directly into the node, I know what I am doing and I don't want any sharding validations or background threads to run".

This flag will make this and this checks conditional on the flag being enabled, so that replica set nodes will not fail to start or start as REMOVED.