Modifying Database Parameters

Purpose

Modify database parameters to improve database performance and reliability.

Procedure

Table 1 describes the tunable parameters in the database configuration file. The default configuration file is /etc/mongodb.cnf. After modifying the configuration file, restart the database for the modification to take effect.

**Table 1** Database parameter tuning
Parameter	Description	Suggestion
cacheSizeGB	Upper limit of the memory used by the WiredTiger engine	If only one MongoDB instance is deployed on a host, set this parameter to 60% of the memory.
Oplog	Size of the oplog used for MongoDB replication	Set it to 5% of the available drive space.
commitIntevalMs	Interval for updating MongoDB journal logs	You are advised to use the default value. A larger value indicates better performance but a higher probability of data loss.
syncPeriodSecs	Interval for flushing data to drives	You are advised to use the default value. A larger value indicates better performance, at the expense of database reliability.
noprealloc	Whether to enable data file pre-allocation	Recommended value: true
noscripting	Whether to enable the script engine	Recommended value: true
notablescan	Whether to allow table scanning	Recommended value: true

Parent topic: Database Tuning