Highly Available LDAP
If updates have been made to the LDAP namespace while the master LDAP server is down, the LDAP databases must be resynchronized prior to restarting the master server. There are two methods for doing this. If a service interruption is possible, the databases can be hand-copied after the LDAP server has been stopped. (Data files are kept by default in /usr/local/var.)
You also can use OpenLDAP replication to restore the database without the service interruption. First, start the LDAP server on the former master node as a slave. Then start slurpd on the current master. Changes received while the former master was out of service are pushed from the new master. Finally, stop the slave LDAP server on the former master node, and start Heartbeat. This results in a failback to the original configuration.
This article outlines a simple example of using open-source software to create some highly available basic network services. Network services including LDAP seldom require huge servers. The additional reliability provided by clustering and the duplication of servers and data files can increase overall service availability. The system worked under all tests, with a failover of less than 15 seconds in all cases. Given a good understanding of system loads and utilization, failover time could be reduced below this threshold.
Thanks to Alan Robertson, IBM Linux Technology Center, for his helpful comments and review.
The foregoing article is based on laboratory tests undertaken in a laboratory environment. Results in particular customer installations may vary based on a number of factors, including workload and configuration in each particular installation. Therefore, the above information is provided on an AS IS basis. The WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY DISCLAIMED. Use of this information is at user's sole risk.
|Free Today: September Issue of Linux Journal (Retail value: $5.99)||Sep 27, 2016|
|nginx||Sep 27, 2016|
|Epiq Solutions' Sidekiq M.2||Sep 26, 2016|
|Nativ Disc||Sep 23, 2016|
|Android Browser Security--What You Haven't Been Told||Sep 22, 2016|
|The Many Paths to a Solution||Sep 21, 2016|
- Free Today: September Issue of Linux Journal (Retail value: $5.99)
- Android Browser Security--What You Haven't Been Told
- Readers' Choice Awards 2013
- Epiq Solutions' Sidekiq M.2
- Downloading an Entire Web Site with wget
- The Many Paths to a Solution
- Securing the Programmer
- Nativ Disc
- Tech Tip: Really Simple HTTP Server with Python
Pick up any e-commerce web or mobile app today, and you’ll be holding a mashup of interconnected applications and services from a variety of different providers. For instance, when you connect to Amazon’s e-commerce app, cookies, tags and pixels that are monitored by solutions like Exact Target, BazaarVoice, Bing, Shopzilla, Liveramp and Google Tag Manager track every action you take. You’re presented with special offers and coupons based on your viewing and buying patterns. If you find something you want for your birthday, a third party manages your wish list, which you can share through multiple social- media outlets or email to a friend. When you select something to buy, you find yourself presented with similar items as kind suggestions. And when you finally check out, you’re offered the ability to pay with promo codes, gifts cards, PayPal or a variety of credit cards.Get the Guide