Designating NICs for MapR

About MAPR_SUBNETS Environment Variable

The MAPR_SUBNETS environment variable can be used to restrict MapR to a subset of NICs. If MAPR_SUBNETS is not set, all IPs are available for all communication. When MAPR_SUBNETS is set on:

• MapR-FS nodes, MapR-FS registers these IP addresses with CLDB as internal IP addresses on which MapR-FS nodes can be reached.
• CLDB nodes, CLDB advertises the IP address to clients on the cluster.

You can set the MAPR_SUBNETS environment variable in the /opt/mapr/conf/env_override.sh file on all the nodes. On the cluster nodes, the value for this environment variable is a comma-separated list of subnet masks. For example:

export MAPR_SUBNETS=10.10.15.0/24,10.10.16.0/24

You can specify up to four NICs in the MAPR_SUBNETS environment variable. If your system has more than four NICs, MapR advertises the first four it finds or if MAPR_SUBNETS environment variable is set, MapR restricts the networks/IPs that are advertised based on the subnets specified therein.

The MAPR_SUBNETS environment variable can be set on the client if there is a NAT between the server and client. On the client host, the value for this environment variable is any one IP address of the client. For example:

export MAPR_SUBNETS=10.11.12.13/32

When specifying the IP address in the MAPR_SUBNETS environment variable on the client host, use /32 to specify a single IP address.

For more information on the MAPR_SUBNETS environment variable, see Environment Variables.

About MAPR_EXTERNAL Environment Variable

If all the IP addresses on the servers are public and can be accessed from outside, the MAPR_EXTERNAL environment variable need not be set. On the other hand, if your cluster nodes have private IP addresses, to allow clients outside the cluster to reach the cluster nodes (such as when MapR is installed on the cloud or Docker container), the public IP addresses can be specified in the MAPR_EXTERNAL environment variable.

On the cluster nodes, you can set this variable in the /opt/mapr/conf/env_override.sh file. When MAPR_EXTERNAL is set on:

• MapR-FS nodes, MapR-FS registers these IP addresses with CLDB as the IP addresses on which external clients can reach MapR-FS nodes. Communication between MapR-FS nodes on the cluster still happen over the internal IP addresses.
• CLDB nodes, CLDB advertises these IPs addresses to clients outside the cluster or data center.

The value for this environment variable is a comma-separated list of IP addresses; you cannot specify the hostname as value. For example:

ip1,ip2,ip3;

For example, you can specify the IP addresses of the IGbE NICs (shown in the illustration above) as the value for this environment variable to allow external or low-performance clients to communicate with the cluster nodes.

export MAPR_EXTERNAL=10.11.0.0

For more information on the MAPR_EXTERNAL environment variable, see Environment Variables.

About IP Addresses for ZooKeeper Nodes

You can specify the IP addresses of ZooKeeper nodes by running the configure.sh utility with both the -Z and -EZ options during cluster configuration and list the:

• Internal IP addresses with the -Z option
• External IP addresses with the -EZ option

When you specify the IP addresses using the -Z and -EZ options, these IP addresses are registered with CLDB and included in the cldb.conf file. In the cldb.conf file, the internal IP addresses set using the -Z option are the values for the cldb.zookeeper.servers parameter and the external IP addresses set using the -EZ option are the values for the cldb.external.zookeeper.servers parameter.

For more information, see configure.sh.

If all the ZooKeepers have different IP addresses, port forwarding is not required and, optionally, you can specify the same port with all the IP addresses. However, in some cases, such as when there is a single external IP address being used by multiple ZooKeepers (as in a Docker container), you can specify ports for ZooKeepers when you run the configure.sh utility with the -Z and -EZ options. For more information, see Specifying Ports.

About Internal and External Clients

Clients communicating with CLDB using internal IP address (of CLDB) are considered internal clients (or clients within the cluster) and clients communicating with CLDB using external IP address (of CLDB) are considered external clients (or clients outside the cluster).

To configure a client as an internal or high-performance client, include CLDB’s internal IP address in the mapr-clusters.conf file on the client host. Similarly, to configure a client as an external or low-performance client, include CLDB’s external IP address in the mapr-clusters.conf file on the client host.

The mapr-clusters.conf file on the client host should not contain both internal and external IP addresses of the server on a cluster. The mapr-clusters.conf file can contain internal and external IP addresses only when the entries in the file on the client host are for multiple clusters. For example, suppose a client, which is an internal client on one cluster and external client on another cluster. The mapr-clusters.conf file on the client host can contain CLDB’s internal IP address for the cluster on which the client is considered an internal client and CLDB’s external IP address for the cluster on which the client is considered an external client.

Limitations

If:

• Both MAPR_SUBNETS and MAPR_EXTERNAL environment variables are set, segregation of NICs for internal and external communication is possible. Internal communication happens over the IP addresses listed in the MAPR_SUBNETS environment variable and external communication happens over the IP addresses listed in the MAPR_EXTERNAL environment variable.
• Only MAPR_SUBNETS environment variable is set, MapR-FS registers the IP addresses (in the MAPR_SUBNETS environment variable) with CLDB as internal IPs.

You can specify up to 4 IP addresses in the MAPR_SUBNETS environment variable 4 IP addresses in the MAPR_EXTERNAL environment variable.