This article explains Reed-Solomon erasure codes and the problems they solve in gory detail, with the aim of providing enough background to understand how the PAR1 and PAR2 file formats work, the details of which will be covered in future articles.

I’m assuming that the reader is familiar with programming, but has not had much exposure to coding theory or linear algebra. Thus, I’ll review the basics and treat the results we need as a “black box”, stating them and moving on. However, I’ll give self-contained proofs of those results in a companion article.

So let’s start with the problem we’re trying to solve! Let’s say you have n files of roughly the same size, and you want to guard against m of them being lost or corrupted. To do so, you generate m parity files ahead of time, and if in the future you lose up to m of the data files, you can use an equal number of parity files to recover the lost data files.

Backupninja allows you to coordinate system backup by dropping a few simple configuration files into /etc/backup.d/. Most programs you might use for making backups don't have their own configuration file format. Backupninja provides a centralized way to configure and schedule many different backup utilities. It allows for secure, remote, incremental filesytem backup (via rdiff-backup), compressed incremental data, backup system and hardware info, encrypted remote backups (via duplicity), safe backup of MySQL/PostgreSQL databases, subversion or trac repositories, burn CD/DVDs or create ISOs, incremental rsync with hardlinking.

Google not only reserves the right to take away or vaporize our data for any reason, but it also reserves the right to discontinue services, the means to access it, whenever it wants. It does this more often than you probably realize and most recently with Google Reader, which disappears on July 1.

If you are familiar with vcs software such as Subversion, you might think of boar as "version control for large binary files". But keep reading, because there is more to it.

Boar stores snapshots of directory trees in a local or remote repository and provides tools to ensure that your data is consistent and complete. You can keep just some or all of your data checked out for viewing and editing.

The repository has a simple layout to ensure that the data can easily be extracted even if the original software should be unavailable. This simplicity makes boar ideal for data that needs safe long-term storage.

Last night, TechCrunch reported that Google will now require sites that import e-mail addresses from Gmail to also allow export of their data. The move was clearly aimed at Facebook, which has kept Google from accessing their users’ data. In response, many people have mentioned that while Facebook lets users download some data, they’re still not able to download an e-mail address book of their Facebook contacts. However, that’s not quite the case. Back in March, I published a guide to exporting data from Facebook using various tricks and FQL queries. Facebook has since made changes and added tools which have made the post a bit outdated, but much of the information still applies. In particular, I described using Yahoo’s contact import tool to download an e-mail address book for all your Facebook friends. This technique relies on a Facebook-approved feature and should not violate the site’s terms of service. A few specific steps have changed a bit, so I’ll recap the process here.

The article discusses how to setup MySQL Replication between two Amazon EC2 instances. It walks you though setting up replication for an empty database server. Adding a slave to a server already full of data is a different article.

It is assumed that you already know the basics of starting EC2 instances, connecting to them via SSH and editing files in Linux using vi/vim etc. For this tutorial, I am using the Amazon built machine image ami-2b5fba42 which is Fedora 8 base image.

The OpenSync project is an ongoing effort to create a synchronization framework that will be a platform independent, general purpose synchronization engine utilizing modular plugins for content formats and different kind of connection types. OpenSync's modularity should allow it to be extended easily to new devices and purposes without radically changing the architecture itself, allowing it to support wide variety of devices used today and in the future.

With libsynthesis, full-featured SyncML functionality based on Synthesis' mature and high quality SyncML DS engine can be integrated into applications. The library provides a stable binary API for both interfacing with the application and for database adaptor plugins.

The Synthesis SyncML engine supports SyncML versions 1.0, 1.1 and 1.2 including complex features like data filtering, suspend & resume, vCard/vCalendar format conversion in a way completely transparent to the user of the library.

Remus provides transparent, comprehensive high availability to ordinary virtual machines running on the Xen virtual machine monitor. It does this by maintaining a completely up-to-date copy of a running VM on a backup server, which automatically activates if the primary server fails. Key features:

* The backup VM is an exact copy of the primary VM. When failure happens, it continues running on the backup host as if failure had never occurred. * The backup is completely up-to-date. Even active TCP sessions are maintained without interruption. * Protection is transparent. Existing guests can be protected without modifying them in any way.

Just drag your Folder into Jake and everything will kept in sync with all people you invite.

Jake is 100% free, open source and available for Linux, Windows and Mac OS X. We're using free technologies like Jabber and open source chat server engines.

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