Backup options

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Backup options

This section provides a high-level overview of the hardware backup options available for Linux and Windows. Much of the hardware is expensive, and the commands depend on what you might buy. A detailed discussion of these options could easily fill a book three times this size.

Media options

Choosing the media that you might use to back up your data depends on the amount of data that you want to keep safe. Individual users who work with text files may need only the space associated with a 1.44MB floppy disk. The same may hold true if you're backing up critical configuration files from the /etc directory, such as inittab, fstab, grub.conf, and the files in the /etc/samba subdirectory.

Note

The /etc/grub.conf file is actually linked to the /boot/grub/grub.conf file. You can open and edit either file name; the result is saved in /boot/grub/grub.conf.

A number of other types of media are available that you can use with a Linux computer. The variations are endless; I cite only the "typical" size for each media type:

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  Zip drives (from Iomega) are normally 100MB and are suitable for backing up other critical files such as the Linux kernel from the /boot directory. If you remember from Chapter 1, the standard Red Hat Linux installation allocates 100MB to the /boot directory.

  
  


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  Bernoulli drives normally include 230MB of space, which might be enough to back up user files from the /home directory on some smaller networks.

  
  
  


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  Writable CD media can store around 650MB of data, which can contain all but the data files for many dedicated Red Hat Linux servers where the GUI is not installed.

  
  


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  Writable DVD media vary in size. They can contain 4.7GB to 17GB of data, which can be used to back up many Linux servers, including data files.

  
  


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  Tape drives are available in a variety of sizes. As of this writing, I've seen single tape drives that can contain up to 300GB of data.

  
  

The media that you select depends on the money you have available, as well as your backup hardware. You also need to consider your specific environment. For example, if the only place where you can store your backups includes a number of magnetic fields (such as a factory or a machine shop), you may want to stick with CDs or DVDs.

System backups

There are a number of ways to back up larger file servers. The most direct way is to use third-party hardware to back up all the data on the server to some high-capacity media. You may also want to back up the hardware associated with your file server. This is possible courtesy of two different open-source projects: the High Availability Linux project and the Linux Virtual Server project.

Third-party hardware

If the hardware on your system, such as a CD or a DVD writer, is not enough, there are a number of third-party options available. For example, some systems can combine dozens of writable CDs, DVDs, and tape drives to save the data from every computer on your network.

A wide variety of hardware options are available. I use the data from www.storagesearch.com in my research. This site is published by Applied Computer Science, Ltd. of the United Kingdom. In addition to those previously described, some of the backup hardware types include:

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  FireWire: One common option is to back up personal computers onto a portable high-capacity hard drive. This type of drive uses connections that correspond to the IEEE1394 standard, also known as iLink. This is essentially a high-speed SCSI connection, which I use to back up data at burst speeds of nearly 400 Mbps. Other types of FireWire drives can write data to other media such as writable DVDs. (Linux support for FireWire as well as the alternative USB 2.0 devices is experimental as of this writing.)

  
  


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  Removable hard drives: If you've configured a RAID 1 array of removable hard drives, you can remove one of the drives in the array and store that drive in some secure remote location. If you have a spare hard drive in that array, a RAID 1 system automatically writes your data to that drive. You can then set up a new hard drive as a spare. Larger groups of removable hard drives are often configured as rack-mount storage.

  
  


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  Jukeboxes: These are "storage cabinets" that allow you to combine the data capacity of a group of media types, such as writable tape, DVDs, and CDs.

  
  
  


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  Storage area networks (SAN): A high-speed network of storage devices; many are in common use for higher-capacity Linux systems. While this isn't explicitly a backup option, it is a common way to organize a RAID system.

  
  

High Availability Linux project

The High Availability Linux project is one way to set up multiple computers as a cluster. The cluster of computers appears like a single server to the other computers on the network. They often share a common external storage medium, usually with a SCSI connection.

If one computer in the cluster fails, another computer takes over automatically. Client computers on the network don't know which computer in the cluster is working as the file server. Because the computers in the cluster share the same external storage, clients see no difference in the data.

While this does not back up your data, it does serve as a backup for your hardware. For example, if you set up a PDC in a cluster, the failure of one computer does not affect your network. For more information on the High Availability Linux project and its "heartbeat" software, navigate to www.linux-ha.org.

Linux Virtual Server project

The Linux Virtual Server project is another way to set up multiple computers as a cluster. This cluster of computers also appears like a single server to the other computers on the network. It also can be configured with a common external storage medium. One additional feature supports load balancing. In other words, if a lot of clients are working through one server in the cluster, load balancing sends additional clients to less busy servers in the cluster.

As with the High Availability Linux project's heartbeat software, if one computer fails, other computers take over automatically. The cluster of computers appears as one file server to the other computers on the network. For more information, see www.linuxvirtualserver.org.

Red Hat Enterprise Linux (RHEL) Advanced Server supports its own version of the Virtual Server project. Red Hat developed its Enterprise Linux distributions from older versions of Red Hat Linux for higher capacity systems. As of this writing, the latest version of RHEL Advanced Server is 2.1, which is based on Red Hat Linux 7.2.

Note

RHEL 3 should be available by the time this book is released. RHEL 3 is based on the primary operating system used in this book, Red Hat Linux 9.