Configuring the MapR POSIX Client

The default RPC requests configuration can negatively impact performance and memory. To avoid performance and memory issues, configure the number of outstanding RPC requests to the cluster to be 128.

Perform the following steps as the root user on each POSIX client machine:

  1. Issue the following commands to create the sunrpc.conf file under /etc/modprobe.d with the recommended configuration:
    echo "options sunrpc tcp_slot_table_entries=128" >> /etc/modprobe.d/sunrpc.conf
    echo "options sunrpc tcp_max_slot_table_entries=128" >> /etc/modprobe.d/sunrpc.conf
    This will enable the configuration to persist after a reboot of the NFS client machine.
  2. Issue the following echo commands:
    echo 128 > /proc/sys/sunrpc/tcp_slot_table_entries
    echo 128 > /proc/sys/sunrpc/tcp_max_slot_table_entries
    This will enable the configuration to take effect after you remount the POSIX client to the MapR cluster.
  3. Remount the POSIX client to the Mapr cluster. For example, the following commands unmount and mount the NFS assuming that the cluster is mounted at /mapr:
    # umount /mapr
    # mount -o hard,nolock 127.0.0.1:/mapr /mapr
    Note: Failure to configure this property may result in the following error in /usr/local/mapr-loopbacknfs/log: ERROR nfsserver[38960] fs/nfsd/requesthandle.cc:791 0.0.0.0[0] cannot allocate more OncRpcContexts: [numDropped=2556001] dropping connection from nfsc=10.13.64.225:0

    CentOS Troubleshooting Tip

    After the reboot of the node, if the /proc/sys/sunrpc directory not available or if rpcidmapd is not running, start the rpcidmapd service using the following command: service rpcidmapd start