Performance Enhancements for SSD Based MapR-DB Deployments
For DB workloads on high-end servers, MapR has made several performance enhancements. For MapR-DB deployments on clusters with SSDs, two fileserver instances are configured on nodes with at least two SPs. On servers with SSDs, this feature is automatically enabled with a fresh install or upgrade.
Required Ports
Ensure that ports 5661 and 6661, as mentioned here, are open and available for this feature. To verify that these ports are open, run the following command from a remote machine:
/opt/mapr/server/mrconfig -i -h <ip> -p <port number> info threads
An error indicates that the port is not open.
Determine Whether the Feature is Enabled
To determine whether this feature is enabled, run the following command:
/opt/mapr/server/mrconfig info instances
Your output will look similar to the following if this feature enabled. This output shows that two fileserver instances are running on ports 5660 and 5661.
# /opt/mapr/server/mrconfig info instances
2
5660 5661
Your output will look similar to the following if the feature is not enabled. It shows that one fileserver instance is running on port 5660.
# /opt/mapr/server/mrconfig info instances
1
5660
Disabling and Enabling the Feature
In certain cases, due to the nature of the workload, you may have to disable this feature. To disable:
- Run the
maprcli config save
command and set the value for themultimfs.numsps.perinstance
parameter to a value greater than the number of SPs on any node in the cluster.For example:
maprcli config save -values {multimfs.numsps.perinstance:500}
NOTE: The default value for this parameter is0
. Changing this parameter can cause INSTANCE_MISMATCH_ALARM to be raised. - Restart fileserver for the configuration changes to take effect and also clear any INSTANCE_MISMATCH_ALARM. To restart, run the following command:
maprcli node services -nodes <node name> -fileserver restart
If you reset the value for multimfs.numsps.perinstance
to
0
or a low number (a number less than the number of SPs on the node),
when Warden is restarted, this feature will be re-enabled and the SPs will be reassigned to
2 MFS instances.
Changes to Log Files
Additional log files are created in $MAPR_HOME/logs
when this feature
enabled. Please make a note of the following:
- There will be two sets of log files, one per instance:
mfs.log-<N>
andmfs.log.<instanceID>-<N>
, where<N>
is greater than 0. For example:mfs.log-3
for the primary instancemfs.log.1-3
for the second instance
- The RPC and security trace information is in these files:
mfs.err
andmfs-1.err
.