Major - P3 With the changes to support chunk filtering on shard secondaries, the primary nodes now persist the collection routing information locally. In the case of read-only shards, these writes are failing benignly, but are polluting the logs with messages like this:
[js_test:count] 2017-06-14T15:34:12.651+0000 d20262| 2017-06-14T15:34:12.415+0000 I SHARDING [ShardServerCatalogCacheLoader-0] OperationFailed: Failed to update the persisted chunk metadata for collection 'test.count' from '4|1||5941576905d04677f27f055f' to '4|1||5941576905d04677f27f055f' due to 'IllegalOperation: Cannot execute a write operation in read-only mode'. Will be retried. [js_test:count] 2017-06-14T15:34:12.652+0000 d20262| 2017-06-14T15:34:12.415+0000 I SHARDING [ShardServerCatalogCacheLoader-0] OperationFailed: Failed to update the persisted chunk metadata for collection 'test.count' from '4|1||5941576905d04677f27f055f' to '4|1||5941576905d04677f27f055f' due to 'IllegalOperation: Cannot execute a write operation in read-only mode'. Will be retried.
This ticket is to come up with a solution to prevent read-only shard primaries from writing the chunk routing table.