Business Continuity

Recovering and protecting data on Mac and Linux desktops

Make sure all of your clients’ computers have a backup plan, whatever operating system they run.

You can’t assume every computer you’re going to deal with for customers will be running Windows any more. Between desirable Mac notebooks and cheap-and-cheerful netbooks, Linux and Mac OS continue to expand their presence in formerly Windows-only networks; and that means you need to worry a bit more about the business-critical data stored onthese machines. While requiring users to put all 
of their data on network drives is great in theory, the reality is that plenty of important data still lives on client computers, and needs to be backed up.

Surprisingly, the mainstream disaster recovery solutions haven’t yet introduced Mac and Linux-compatible agents, meaning you’re unlikely to simply be integrating disaster recovery for these machines into your existing scheme. Fortunately, there’s no shortage of third-party solutions designed to run directly on Mac and Linux client computers and help protect them from disaster.

Protecting Macs

Mac computers running Mac OS X 10.5 or later (nicknamed ‘Leopard’) have access to a fantastic built-in recovery feature called Time Machine. The feature requires either a locally-connected external hard drive (either USB or FireWire) or Apple’s Time Capsule (which is a combination Wi-Fi access point and hard drive). Many people have successfully used Time Machine with Windows-based shared folders, as well: you need to open a terminal window and type

defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1

To let Time Machine see network drives. If you run into problems, check out the comprehensive instructions for making Time Machine work with a Windows share at www.flokru.org/2008/02/29/time-machine-backups-on-network-shares-in-leopard/


Time Machine presents a simplified, chronological view of a folder to help users locate the files they need to recover. It is integrated into file management as well as the Mac’s native calendar and other applications.

New models of HP’s Windows Home Server system, the HP MediaSmart Server ex485 and ex487, will work with Time Machine out of the box (though you will have to install the client software on each Mac). An update will be available for existing models to add Time Machine support. That makes Home Server an attractive option for a small office with both Macs and PCs; see page 38 for more details.

Time Machine runs an initial full backup of the computer, and then runs hourly incremental backups. It permits individual file recovery through a graphical chronological interface, making it easy for users to recover files and folders that they’ve accidentally deleted, or to recover older versions of files that have changed. Time Machine can be configured to use a maximum amount of disk space; once that space is used, it will begin discarding older backups to make room for new ones. If it sounds familiar, it’s because it’s roughly analogous to volume shadow copy and the Previous Versions feature in Windows Vista, although less-experienced users may find the Time Machine interface more intuitive than right-clicking in a folder.

Time Machine backups can also be used to recover the computer from a total failure: When installing the operating system from the Mac OS DVDs, you’ll see an option to recover from a Time Machine backup.

Time Machine’s initial backup can be quite time- and bandwidth-consuming. Depending on network speeds and the amount of data on the Mac, it may require ten or more hours to complete. After that, the hourly incremental backups usually take only a few minutes. Selected folders on the Mac can be excluded from Time Machine’s backup, if desired. Time Machine’s configuration is simple and its operation is completely automatic. As a built-in feature, it’s a good choice for Mac disaster recovery.

Protecting Linux

While most variants of Linux include some primitive built-in backup capabilities, you’ll want a more manageable and robust solution. One offering is BRU Desktop for Linux/Unix from Tolis Group (£72–272 depending on the flavour of Linux and number of licences). Designed to work with locally-attached external drives, it’s perfect for small-to-medium environments where you don’t want to develop an extensive disaster recovery infrastructure (Tolis offers alternative solutions for organisations with larger networks and client computer populations). 

Thanks to Linux’s open-source heritage, a number of open-source utilities and software applications are available to help with disaster recovery. Most of these require a bit more work to implement, which means you need to be comfortable with Linux shell scripts and utilities. Partimage clones entire partitions from Linux hard drives, but only grabs used disk space when doing so. That means a 100GB partition which is only half-used will only require 50GB for its clone; combined with Linux’s built-in gzip compression tool, a 50GB clone might require only 20GB of disk storage. 


KDar offers a graphical wrapper around the Linux Dar utility, making backups easier to create and manage. Both KDar and Dar are free.

If you’re not interested in writing your own shell scripts, there are other open-source alternatives that offer graphical user interfaces. For example, one Linux utility commonly used for backups is Dar (which stands for Disk Archive); a graphical shell called KDar is available for Linux systems running the KDE graphical desktop environment. KDar makes desktop backups a bit more point-and-click, and works with any form of locally-connected storage or network drives. There’s a good tutorial on using KDar at www.linux.com/feature/113913

There are many third-party solutions available for high-end Linux backup and restore, but most of these focus on Linux servers, rather than desktops. Perhaps because of Linux’s open-source appeal and the typically high level of technical knowledge possessed by most Linux fans (who often prefer to script their own backup solution), there are remarkably few commercial desktop disaster recovery applications for the operating system. Most commercial solutions focus on network-based backup, such as Zmanda Amanda, a solution that supports Mac, Linux, and Windows clients being backed up to a Linux-based server, and then to tape, disk, or online storage. 

There are few Linux-specific online backup services, although Linux makes it straightforward to use any kind of online storage (such as Amazon S3) as a backup service; a tutorial at www.harmonyservice.com/content/view/27/40/ explains the necessary steps. 

Protecting everything

One of the few major manufacturers to support heterogeneous clients is EMC Insignia, the software division of storage giant EMC. Their Retrospect product (formerly produced by Dantz Development) is offered in both Windows and Mac flavours, and is designed to run on a centralised network server running either Windows or Mac OS X. Either edition is capable of backing up Windows, Mac OS X, and Red Hat Linux clients (and both are priced around £499). Both editions enable bare-metal restores as well as individual file recovery, although this typically needs to be done rather by an administrator rather than allowing the user to recover their own files. The Windows edition also supports SUSE Linux, Solaris, and NetWare computers. 

EMC is currently developing Retrospect X, a Mac-specific solution that offers advanced features such as disk-to-disk-to-tape backups, continuous backups, stronger encryption, and other capabilities which make it more parallel to Retrospect for Windows. 


Tolis Group, the developer of BRU Desktop for Linux and Unix, also produces server-class disaster recovery solutions capable of reaching out to Mac, Windows, and Linux client computers. Server software is available for both Mac and Linux/Unix-based servers. Zmanda’s solution is also network-based and includes clients for Mac, Linux, and Windows computers.

Even backup drives fail

Managing desktop-based backup applications can be time-consuming. If you have relatively few Mac computers to look after, for example, equipping each of them with an external FireWire drive and relying on Time Machine may be acceptable. However, if you have a dozen Mac computers at a site, worrying about all those external drives – and potential drive failures that take your backups with them – may not be acceptable. If you have a mix of Linux and Mac computers, desktop-based backups may be even less palatable given the general lack of robust commercial solutions that would provide a similar set of capabilities and experiences across both platforms. Particularly in mixed environments, many organisations will prefer to centralise backups on the network, and there’s another benefit to consolidating Windows, Mac, and Linux client backups into a single location, a single process, and a single set of capabilities and experiences. Having one way to provide disaster recovery can take much of the pain out of heterogeneous platform management: simpler for you and better for your clients.
 
 

Time Machine: 

www.apple.com/support/leopard/timemachine/

Retrospect Mac:


BRU Desktop:


Partimage:


Zmanda: 


Time Machine backups on network shares: possible problems:

 


 
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