Configuring MAPR_SUBNETS for FUSE-based POSIX Client

Describes how the to configure MAPR_SUBNETS and MAPR_SOURCE_HONOUR_SUBNETS environment variables to control client–server storage traffic, such that the client-server communication is restricted to the specified subnet only.

Export the following environment variables on the FUSE-based POSIX client node using the FUSE init script:

Variable Purpose
MAPR_SUBNETS Specifies the subnet(s) the client should use, comma separated (e.g., "196.171.4.0/24,172.23.46.0/24")
MAPR_SOURCE_HONOUR_SUBNETS Set to true to enable client-side subnet enforcement. The default value is false which implies that the kernel selects interface for communication regardless of the subnets specified in the MAPR_SUBNETS environment variable.
Follow the steps given below to control FUSE-based POSIX client–server communication:
  1. Add the export statements to the do_start() function in the /opt/mapr/initscripts/mapr-fuse initscript:
    export MAPR_SUBNETS="192.168.4.0/24"
export MAPR_SOURCE_HONOUR_SUBNETS="true"
  2. Save and close the mapr-fuse file.
  3. Restart the FUSE-based POSIX client.
REMEMBER
  • Any node in the cluster should be routable from every subnet listed in MAPR_SUBNETS. Verify routing on all nodes before enabling.
  • When an interface listed in MAPR_SUBNETS goes down on a FUSE-based POSIX client, ongoing I/O may stall for several minutes before failing over to another interface. The delay occurs because existing TCP connections continue retrying until kernel timeouts expire. Users requiring faster failover should tune TCP retry settings appropriately.