Easy Backups with AMANDA

Moderation is good in almost all things, but there are a few things you just can’t overdo: Case in point, backups. It’s virtually impossible for your data to be too well backed-up or to have too many copies of your important files. It’s also a good thing to have a lot of options when it comes to backup software, which is why I’m talking about AMANDA this month.

Previously, I showed you how to create local and remote filesystem snapshots using rsnapshot. In that article, I promised to cover a more traditional Open Source backup application in the future. In this column I will be covering AMANDA, the Advanced Maryland Automatic Network Disk Archiver.

With development dating back to 1991, Amanda is one of the oldest and most popular Open Source backup utilities. Amanda allows you to set up a single server to back up multiple networked clients to a tape or disk-based storage system easily. It even allows you to write backups to tape and disk simultaneously, allowing for on-line quick restores from disk and off-site storage for disaster recovery and long-term retention.

Unlike many backup applications, Amanda does not use any proprietary device drivers, meaning any device supported by your operating system should work. From a client perspective, Amanda supports all major UNIX variants as well as Max OS X and Microsoft Windows. Backups are stored in a format that allows for easy recovery with native Linux tools, which can come in quite handy in a pinch. From a security perspective, encryption on a client can ensure security of data in transit and encryption on a backup server can ensure security of data during storage.

Since backup procedures and policies are very specific to individual environments, I’ll cover a basic scenario in this column. The Amanda documentation is extremely thorough and should be able to accommodate any setup you are considering. As binary packages are provided for most major distributions, we will not cover installation from source. I’ll leave items such as encryption as an exercise for the reader.

First, we’ll need to install the Amanda server package on the system we’ll be using as a backup server. Remember you can backup to tape, disk, or both. An intermediate holding area for caching data is not absolutely necessary, but will improve performance significantly and is a best practice. The installation process will create an amandabackup user and should add amandad to your xinetd configuration.

It’s now time to install the Amanda client on any machines you’d like to backup. The installation process will once again create an amandabackup user and should add amandad in a client configuration to your xinetd. Next, create a file named /var/lib/amanda/.amandahosts with the permissions 0700. The file should contain the following:

backuphost.yourdomain.com amandabackup amdump

To backup a Windows client you can either use Samba to mount the Windows machine on the backup server or use the Windows MSI available from the Zmanda site. With Amanda now installed and running on both the client and server it’s time to configure the server.

First, copy the example configuration script to the Amanda configuration directory. Like many example configuration files shipped with Open Source applications, the file is very heavily commented. Once you are more familiar with Amanda you can skip this step and simply create your configuration from scratch, but if this is your first Amanda install the example is the best place to start.

# cp /var/lib/amanda/example/amanda.conf /etc/amanda/DailySet1

The Amanda wiki is a great place to get additional information on the configuration directives. Here are a few of the basic directives you’ll need for a disk based backup.

org "YourCompanyName"
mailto "backup-admin@yourdomain.com"
tapetype HARDDISK
tpchanger "chg-disk"
tapedev "file://path/to/backups/DailySet1/slots"

define tapetype HARDDISK {
 length 10000 mbytes
}

Next, create /etc/amanda/DailySet1/disklist with a list of clients you’d like to backup:

machine.yourdomain.com /path/to backup dumptype

As with the client, you’ll also need to create /var/lib/amanda/.amandahosts.

machine.yourdomain.com root amindexd amidxtaped

You are now ready to create your virtual tape. Next, verify you can successfully perform a backup.

$ amcheck DailySet1

You can now use to perform a backup. You'll want to add this to cron once your setup is complete. As with any backup installation procedure, you should fully test a restore before you consider your setup complete.

Using Amanda allows you quickly and easily implement a robust Open Source backup solution. You can back up to almost any device, or even multiple devices simultaneously. You even have multiple options, including Zmanda, if you’d like commercial support or professional services.