Step 1: Setting Up Hosts and the Load Balancer

At a high level, you set up Cloudera Manager Server and Cloudera Management Service roles (including Cloudera Navigator) on separate hosts, and make sure that network access to those hosts from other Cloudera services and to the Admin Console occurs through the configured load balancer.

Creating Hosts for Primary and Secondary Servers
Setting up the Load Balancer
Setting up the Database
Setting up an NFS Server

Cloudera Manager Server, Cloudera Navigator, and all of the Cloudera Management Service roles that use a relational database should use an external database server, located off-host. You must make sure that these databases are configured to be highly available. See Database High Availability Configuration.

You configure other Cloudera Management Service roles (such as the Service Monitor and Host Monitor roles) that use a file-backed storage mechanism to store their data on a shared NFS storage mechanism.

High-level layout of components for Cloudera Manager high availability

Creating Hosts for Primary and Secondary Servers

For this example, Cloudera recommends using four hosts for Cloudera Manager services. All of these hosts must resolve forward and reverse DNS lookups correctly:

Cloudera Manager Server primary host (hostname: CMS1)
Cloudera Management Service primary host (hostname: MGMT1)
Cloudera Manager Server secondary host (hostname: CMS2)
Cloudera Management Service secondary host (hostname: MGMT2)

In addition, Cloudera recommends the following:

Do not host the Cloudera Manager or Cloudera Management Service roles on existing hosts in a CDH cluster, because this complicates failover configuration, and overlapping failure domains can cause problems with fault containment and error tracing.
Configure both the primary and the secondary hosts using the same host configuration. This helps to ensure that failover does not lead to decreased performance.
Host the primary and secondary hosts on separate power and network segments within your organization to limit overlapping failure domains.

Setting up the Load Balancer

This procedure demonstrates configuring the load balancer as two separate software load balancers using HAProxy, on two separate hosts for demonstration clarity. (To reduce cost, you might prefer to set up a single load balancer with two network interfaces.) You use one HAProxy host for Cloudera Manager Server and another for the Cloudera Management Service.

Reserve two hostnames in your DNS system, and assign them to each of the load balancer hosts. (The names CMSHostname, and MGMTHostname are used in this example; substitute the correct hostname for your environment.) These hostnames will be the externally accessible hostnames for Cloudera Manager Server and Cloudera Management Service. (Alternatively, use one load balancer with separate, resolvable IP addresses—one each to back CMSHostname and MGMTHostname respectively).
- CMSHostname is used to access Cloudera Manager Admin Console.
- MGMTHostname is used for internal access to the Cloudera Management Service from Cloudera Manager Server and Cloudera Manager Agents.
Set up two hosts using any supported Linux distribution (RHEL, CentOS, Ubuntu or SUSE; see CDH and Cloudera Manager Supported Operating Systems) with the hostnames listed above. See the HAProxy documentation for recommendations on configuring the hardware of these hosts.
Install the version of HAProxy that is recommended for the version of Linux installed on the two hosts:
RHEL/CentOS:
```
$ yum install haproxy
```
Ubuntu (use a current Personal Package Archive (PPA) for 1.5 from http://haproxy.debian.net):
```
$ apt-get install haproxy
```
SUSE:
```
$ zypper install haproxy
```
Configure HAProxy to autostart on both the CMSHostname and MGMTHostname hosts:
RHEL, CentOS, and SUSE:
```
$ chkconfig haproxy on
```
Ubuntu:
```
$ update-rc.d haproxy defaults
```

Configure HAProxy.

On CMSHostname, edit the /etc/haproxy/haproxy.cfg files and make sure that the ports listed at Ports Used by Cloudera Manager and Cloudera Navigator for “Cloudera Manager Server” are proxied. For Cloudera Manager, this list includes the following ports as defaults:

7180
7182
7183

Sample HAProxy Configuration for CMSHostname

listen cmf :7180
    mode tcp
    option tcplog
    server cmfhttp1 CMS1:7180 check
    server cmfhttp2 CMS2:7180 check

listen cmfavro :7182
    mode tcp
    option tcplog
    server cmfavro1 CMS1:7182 check
    server cmfavro2 CMS2:7182 check

#ssl pass-through, without termination
listen cmfhttps :7183
    mode tcp
    option tcplog
    server cmfhttps1 CMS1:7183 check
    server cmfhttps2 CMS2:7183 check

On MGMTHostname, edit the /etc/haproxy/haproxy.cfg file and make sure that the ports for Cloudera Management Service are proxied (see Ports Used by Cloudera Manager and Cloudera Navigator). For Cloudera Manager, this list includes the following ports as defaults:

5678
7184
7185
7186
7187
8083
8084
8086
8087
8091
9000
9994
9995
9996
9997
9998
9999
10101

Example HAProxy Configuration for MGMTHostname

listen mgmt1 :5678
    mode tcp
    option tcplog
    server mgmt1a MGMT1 check
    server mgmt1b MGMT2 check

listen mgmt2 :7184
    mode tcp
    option tcplog
    server mgmt2a MGMT1 check
    server mgmt2b MGMT2 check

listen mgmt3 :7185
    mode tcp
    option tcplog
    server mgmt3a MGMT1 check
    server mgmt3b MGMT2 check
listen mgmt4 :7186
    mode tcp
    option tcplog
    server mgmt4a MGMT1 check
    server mgmt4b MGMT2 check
listen mgmt5 :7187
    mode tcp
    option tcplog
    server mgmt5a MGMT1 check
    server mgmt5b MGMT2 check

listen mgmt6 :8083
    mode tcp
    option tcplog
    server mgmt6a MGMT1 check
    server mgmt6b MGMT2 check
listen mgmt7 :8084
    mode tcp
    option tcplog
    server mgmt7a MGMT1 check
    server mgmt7b MGMT2 check
listen mgmt8 :8086
    mode tcp
    option tcplog
    server mgmt8a MGMT1 check
    server mgmt8b MGMT2 check
listen mgmt9 :8087
    mode tcp
    option tcplog
    server mgmt9a MGMT1 check
    server mgmt9b MGMT2 check
listen mgmt10 :8091
    mode tcp
    option tcplog
    server mgmt10a MGMT1 check
    server mgmt10b MGMT2 check
listen mgmt-agent :9000
    mode tcp
    option tcplog
    server mgmt-agenta MGMT1 check
    server mgmt-agentb MGMT2 check
listen mgmt11 :9994
    mode tcp
    option tcplog
    server mgmt11a MGMT1 check
    server mgmt11b MGMT2 check
listen mgmt12 :9995
    mode tcp
    option tcplog
    server mgmt12a MGMT1 check
    server mgmt12b MGMT2 check
listen mgmt13 :9996
    mode tcp
    option tcplog
    server mgmt13a MGMT1 check
    server mgmt13b MGMT2 check
listen mgmt14 :9997
    mode tcp
    option tcplog
    server mgmt14a MGMT1 check
    server mgmt14b MGMT2 check
listen mgmt15 :9998
    mode tcp
    option tcplog
    server mgmt15a MGMT1 check
    server mgmt15b MGMT2 check
listen mgmt16 :9999
    mode tcp
    option tcplog
    server mgmt16a MGMT1 check
    server mgmt16b MGMT2 check
listen mgmt17 :10101
    mode tcp
    option tcplog
    server mgmt17a MGMT1 check
    server mgmt17b MGMT2 check

After updating the configuration, restart HAProxy on both the MGMTHostname and CMSHostname hosts:

$ service haproxy restart

Setting up the Database

Create databases on your preferred external database server. See Step 4: Install and Configure Databases.
Important: The embedded Postgres database cannot be configured for high availability and should not be used in a high-availability configuration.
Configure your databases to be highly available. Consult the vendor documentation for specific information.
MySQL, PostgreSQL, and Oracle each have many options for configuring high availability. See Database High Availability Configuration for some external references on configuring high availability for your Cloudera Manager databases.

Setting up an NFS Server

The procedures outlined for setting up the Cloudera Manager Server and Cloudera Management Service hosts presume there is a shared store configured that can be accessed from both the primary and secondary instances of these hosts. This usually requires that this store be accessible over the network, and can be one of a variety of remote storage mechanisms (such as an iSCSI drive, a SAN array, or an NFS server).

This section describes how to configure an NFS server and assumes that you understand how to configure highly available remote storage devices. Further details are beyond the scope and intent of this guide.

There are no intrinsic limitations on where this NFS server is located, but because overlapping failure domains can cause problems with fault containment and error tracing, Cloudera recommends that you not co-locate the NFS server with any CDH or Cloudera Manager servers or the load-balancer hosts detailed in this document.

Install NFS on your designated server:

RHEL/CentOS

$ yum install nfs-utils nfs-utils-lib

Ubuntu

$ apt-get install nfs-kernel-server

SUSE

$ zypper install nfs-kernel-server

Start nfs and rpcbind, and configure them to autostart:

RHEL/CentOS:

$ chkconfig nfs on
$ service rpcbind start
$ service nfs start

Ubuntu:

$ update-rc.d nfs defaults
$ service rpcbind start
$ service nfs-kernel-server

SUSE:

$ chkconfig nfs on
$ service rpcbind start
$ service nfs-kernel-server start

High-Level Steps to Configure Cloudera Manager High Availability

Step 2: Installing and Configuring Cloudera Manager Server for High Availability