mongod.conf oplogInitialFindMaxSeconds parameter

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Joe Piscitella

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Sep 25, 2018, 11:39:48 AM9/25/18

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Trying to start mongod with

# /usr/local/mongodb-linux-x86_64-3.6.8/bin/mongod --quiet --config /etc/mongodb.conf --pidfilepath /var/run/mongodb/mongodb.pid --fork

Unrecognized option: replication.oplogInitialFindMaxSeconds

# /usr/local/mongodb-linux-x86_64-3.6.8/bin/mongod --quiet --config /etc/mongodb.conf --pidfilepath /var/run/mongodb/mongodb.pid --fork

Unrecognized option: oplogInitialFindMaxSeconds

try '/usr/local/mongodb-linux-x86_64-3.6.8/bin/mongod --help' for more information

replication:

oplogSizeMB: 102400

replSetName: eqbill2-shard1set

# oplogInitialFindMaxSeconds: 120

setParameter:

wiredTigerConcurrentReadTransactions : 256

wiredTigerConcurrentWriteTransactions : 256

sharding:

clusterRole: shardsvr

#oplogInitialFindMaxSeconds: 120

#replication.oplogInitialFindMaxSeconds: 120

Kevin Adistambha

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Oct 1, 2018, 11:49:29 PM10/1/18

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Hi Joe

Unrecognized option: replication.oplogInitialFindMaxSeconds

This is because oplogInitialFindMaxSeconds is part of the server parameter and not part of valid configuration settings in a config file. See MongoDB Server Parameters for more details.

Having said that, those are advanced configuration setting, along with:

wiredTigerConcurrentReadTransactions : 256
wiredTigerConcurrentWriteTransactions : 256

Is there a reason why the WiredTiger read/write tickets are set to 256 instead of their default 128? Are you facing issues that the default settings do not suffice? Typically, it is not recommended to change advanced default settings such as WiredTiger read/write tickets, since it can have negative consequences for your performance.

In terms of WiredTiger read/write tickets, bigger is definitely not better. This is essentially saying that your physical machine can handle 256 simultaneous read/write operations, which the typical server hardware cannot do. As a result in busy times, it may lead to “stalls” in the WiredTiger engine since it’s trying to force the machine to do the work it realistically cannot do.