The following sections provide information about configuration changes that MapR makes to each node during installation.

TCP Windowing Parameters

Setting certain TCP windowing parameters has shown to increase performance. As of version 2.1.3, MapR changes the parameters shown in the following table.

ParameterOld ValueNew Value
4096 87380 6291456
4096 1048576 4194304
4096 16384 4194304
4096 1048576 4194304
190761 254349 381522
8388608 8388608 8388608


As of version 3.1, MapR changes the configuration of SELinux from Enforcing to Permissive, and disables iptables.

# chkconfig iptables --list
iptables           0:off    1:off    2:off    3:off    4:off    5:off    6:off
# getenforce

Changes Made by the Script

When you run the script to perform initial configuration for your cluster, the script creates a group named shadow if that group does not already exist, then sets the shadow file and the mapr user's group membership to shadow. The script then modifies the permissions for /etc/shadow to grant read access to the shadow group. These changes are required to enable Pluggable Authentication Modules (PAM) to validate user authentication.