LDM Bridge

Contents

Overview
RPM Install
Building and Installing
Remaining work on this project
Support and Bug Tracking

Overview

The DRLB LDM service is a front-end load balancer for the Unidata LDM (Local Data Manager) protocol.

The DRLB LDM service uses your existing ldmd.conf (plus include files) to allow or deny incoming client requests to LDM product feeds. The DRLB LDM server listening on port 388 routes LDM requests and data to any number of back-end clients. Each back-end client runs an LDM server. The ldmd.conf ALLOW and ACCEPT rules are applied by the front-end load balancer. If the incoming client request does not have matching ALLOW or ACCEPT rule the front-end LB drops the client connection. If the client request for a feed type does not match any ALLOW rules, with optional OK and NOT patterns, the front-end LB drops the client connection. If a client sends a product and the incoming product does not match any ACCEPT rules the client connection is dropped. Client connections meeting the ALLOW and/or ACCEPT criteria are forward on to a back-end LDM server in accordance with the LB scheme. By using the front-end LB to process initial LDM client requests we conserve CPU, memory, and network resources on all back-end LDM servers. This methodology also allows you to run the latest version of LDM on back-end clients without having to delay upgrades due to clients running old versions of LDM.

DRLB source code is distributed as an open source project under the GNU general public license and can used by freely by commercial, Government, and academic institutions.

RPM Install

Latest pre-built RPMs are available for download:

RHEL9:
https://github.com/datareel/LDM-load-balancer/releases/download/1.63/drlb_ldm_server-1.63-1.el9.x86_64.x86_64.rpm
sha256sum: d8ae3f9fb49154c8b2f7ac6af0c9f0ffc5b9004579e5414a76ca42715158c4e2

RHEL8:
https://github.com/datareel/LDM-load-balancer/releases/download/1.63/drlb_ldm_server-1.63-1.el8.x86_64.x86_64.rpm
sha256sum: f443ad23106b7925bcb16eb924cbf92c598203e3edd73662d6c0a0a54ba26d2f

RHEL7/CENTOS7:
https://github.com/datareel/LDM-load-balancer/releases/download/1.62/drlb_ldm_server-1.62-1.el7.x86_64.x86_64.rpm
sha256sum: 24618567d351e4017a9e65c3ed5d76ab8ae7ede054314d2ba5c57959818acb4c

RHEL6/CENTOS6:
https://github.com/datareel/LDM-load-balancer/releases/download/1.62/drlb_ldm_server-1.62-1.el6.x86_64.x86_64.rpm
sha256sum: 95ee13f9174340f7bb07a3a942a04e9bb715d457a13d2d70c3153eec03f7f944

Follow the instructions below to build an RPM from latest source code for distribution:

$ cd $HOME; mkdir -pv git; cd $HOME/git
$ git clone https://github.com/datareel/LDM-load-balancer
$ cd ${HOME}/git/LDM-load-balancer/rpm_builder

RHEL9:

$ ./make_ldm_rpm_package.sh rhel9
$ sudo su root -c "yum -y install ${HOME}/rpmbuild/RPMS/x86_64/drlb_ldm_server-1.63-1.el9.x86_64.x86_64.rpm"

RHEL8:

$ ./make_ldm_rpm_package.sh rhel8
$ sudo su root -c "yum -y install ${HOME}/rpmbuild/RPMS/x86_64/drlb_ldm_server-1.63-1.el8.x86_64.x86_64.rpm"

RHEL7/CENTOS7:

$ ./make_ldm_rpm_package.sh rhel7
$ sudo su root -c "yum -y install ${HOME}/rpmbuild/RPMS/x86_64/drlb_ldm_server-1.63-1.el7.x86_64.x86_64.rpm"

RHEL6/CENTOS6:

$ ./make_ldm_rpm_package.sh rhel6
$ sudo su root -c "yum -y install ${HOME}/rpmbuild/RPMS/x86_64/drlb_ldm_server-1.63-1.el6.x86_64.x86_64.rpm"

Useful RPM command to verify package contents:

List package: rpm -qf /usr/sbin/drlb_ldm_server
List files: rpm -ql drlb_ldm_server
List configs: rpm -qc drlb_ldm_server
List docs: rpm -qd drlb_ldm_server

To remove package:

$ sudo su root -c "yum -y remove drlb_ldm_server"

Building and Installing

Follow the instructions below to build and install the DRLB LDM server from latest source code:

$ cd $HOME
$ mkdir -pv git
$ cd $HOME/git
$ git clone https://github.com/datareel/LDM-load-balancer
$ source $HOME/git/LDM-load-balancer/env/gnu_env.sh
$ cd $HOME/git/LDM-load-balancer/drlb_ldm
$ make
$ sudo su root -c 'make install_root'

The DRLB LDM service must have access to your LDM configuration, the default location is:

/usr/local/ldm/etc/ldmd.conf

NOTE: On the front-end LDM you will not be running the LDM server. If you want to store your ldmd.conf (plus any include files) in another local you can modify the LB configuration to point to another location.

The default LB configuration file for LDM clusters is:

/etc/drlb/ldm_cluster.cfg

In the LB configuration file, refer to the following section for all settings specific to DRLB LDM:

[LDMCONFIG]
ldm_etc_dir = /usr/local/ldm/etc
ldmd_conf_file = ldmd.conf
resolve_ldm_hostnames = 1

For all other DRLB setting please refer to the DRLB README file:

# more /usr/share/doc/drlb_ldm/README.txt

or online:

http://datareel.com/drlb/

The default LB scheme used with LDM is assigned. The default assignment rules file is:

/etc/drlb/ldm_cluster_rules.cfg

The assignment rules allow you to route LDM requests to specific back-end servers. This is done to isolate clients making excessive requests or manage clients with unique requirements. By default if the assigned back-end LDM server is down, the client request will be forward to the next available back-end LDM server.

After setting up your LB and LDM configuration files, start the service:

RHEL 7/CENTOS 7:

# systemctl start drlb_ldm_server
# systemctl status drlb_ldm_server

RHEL 6/CENTOS 6:

# service drlb_ldm_server start
# service drlb_ldm_server status

To watch the log file:

# tail -f /var/log/drlb/ldm_cluster_lb.log

To watch LB stats:

# tail -n 25 -f /var/log/drlb/ldm_cluster_lb_stats.log

To make the LB service persistent:

RHEL 7/CENTOS 7:

# systemctl enable drlb_ldm_server

RHEL 6/CENTOS 6:

# chkconfig drlb_ldm_server on

Remaining work on this project

Support and Bug Tracking

https://github.com/datareel/LDM-load-balancer/issues