Linux Data Replication Methods For High Availability

Many Linux servers have critical data that must be available from a redundant source in case the primary server fails. Sometimes this requires a high availability cluster, and sometimes it just requires of copy of the data somewhere else. When configuring some form of data replication on a Linux server, an important point to consider is the nature of the data itself. Sometimes this can severely limit the replication methods available to you.

I recently spoke with a System Administrator who wanted a general purpose replication scheme that could be used on any kind of data. He wasn’t sure what kinds of data he would eventually want to replicate, and really just wanted to cover his bases and make sure that if he chose our product it would have broad applicability within his datacenter. As it turns out, this led to an interesting discussion of what replication methods are best for different types of data, and why.

Asynchronous vs. Synchronous

Generally speaking there are two choices. The first and easiest way is to replicate files asynchronously with a tool like rsync. This can be as simple as running rsync manually or via cron every once in a while, or as complicated as having custom tools that watch for changes in your data and automatically synchronize machines when changes are detected. There is a kernel feature called Inotify that can help with the latter if you want to write your own custom app to perform certain actions when specified files or directories change. Whether you keep it simple or not, this method is nice because the fact that you are replicating data won’t slow down your application. But on the downside, the data is not replicated immediately. Whether the delay is one second or one day, there is still a delay and if you have a failover, you can be assured that your secondary server is not guaranteed to pick up the data where the first server left off.

Read more via Linux Data Replication Methods For High Availability.

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One Response

  1. Check out EnduraData’s heterogeneous operating system file replication at
    http://www.enduradata.com

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