Take Control of Mac OS X Backups: The Online Appendixes

One of the first questions you may ask about a backup program is whether it can store your files where you want them to go—the destination, sometimes called a “target.” This could be a hard disk, a recordable DVD, another Mac on your local network, or a server on the Internet, among other examples. In most cases, I prefer to use an external hard drive as a destination, but other options are sometimes worthwhile. For example, recordable optical discs are useful for inexpensive long-term storage or backups while on the road, and online storage services provide both convenience and security (though often at the cost of a rather slow speed). This table shows which programs can back up to which kinds of destinations, and gives a few related details. As always, click a column heading for more information about the feature being described.

Note: The top portion of the table lists programs that offer bootable duplicates, versioned backups, or both. The bottom portion of the table lists other backup, synchronization, and file copying tools. Enterprise-grade software is not shown here.

Last updated: August 14, 2010

Feature Explanations for This Table

Hard Disk: Almost all backup programs can store backups on an internal or external hard disk. (Notable exceptions include most of those that are tied to online backup services.)

Disk Image: Disk images are useful as containers that can organize, compress, and/or encrypt backups, and sometimes divide them into chunks of specific sizes (for later burning onto CD/DVD, for example). Some backup programs (see the Notes column) always store backups in disk images, though that image may itself be located on various other media. Some programs optionally create disk images in lieu of storing “raw” files directly on the media. And many can store files on disk images only if you’ve manually created them using Disk Utility and mounted in the Finder (footnote [a]), though that strikes me as more hassle than I'd want to endure on a regular basis.

CD/DVD: Some backup programs can write directly to your Mac’s SuperDrive or other optical drive. Others have “built-in” support for optical media in the sense that you can choose your optical drive as a destination directly within the program, but the software still relies on Mac OS X’s disc burning mechanisms (and inherits its limitations). Both of the foregoing categories merit a “Yes” in this column. Many backup programs, though (marked with footnote [b]), can save files to an optical disc in a roundabout way: you put a disc in, mount it in the Finder, choose it as your backup destination, and then, after the backup has run, use the Finder to burn it.

Add Disc Data: Although rare, a few programs have either multisession support (for writing multiple sessions of data to a single recordable disc, even if it’s not rewritable) or packet-writing support (in which the program writes data directly to the disc in small segments rather than in full-blown sessions). In some cases, you can get the equivalent of multisession support even if your software doesn’t natively support it by using a utility called BurnAgain FS from freeridecoding (15 €—about $23).

Media Spanning: If your backup (or, in some cases, a single file) is too large to fit on a single CD or DVD, some backup programs can split it so that it spans more than one disc.

Network Servers (Finder-Mounted): Most backup programs can save your files to any volume that’s mounted in the Finder—including other Macs using Personal File Sharing (AFP), PCs sharing disks with Samba (SMB), and WebDAV servers. However, beware: the fact that your backup program lets you store your files on one of these servers doesn’t guarantee that your data will be stored intact. In particular, some non-Mac network volumes are likely to munge resource forks and other Mac file metadata unless the backup program takes special pains to enclose your data in a disk image or other archive file to preserve all those bits and pieces.

Automount: Most network servers require you to enter a user name and password to mount them. Some backup programs can store your login credentials for the backup server and automatically mount it for you when your backups run, saving you the hassle of doing this manually beforehand.

iDisk: Almost without exception, any program that can store backups in a Finder-mounted network volume can use your iDisk too (if you’re a MobileMe member), because that’s what it is: a WebDAV volume mounted in the Finder. However, a few programs have native iDisk suport—allowing you to choose iDisk as a destination directly, (usually) storing your login credentials, and in some cases automatically storing your backups in your iDisk’s Backups folder.

Other Online Storage: If you have an account on a network server that uses protocols such as FTP, SFTP, SSH, or WebDAV, you can to back up your files directly to them by using a program that supports the protocol you need. (Note that FTP is an inherently insecure protocol. Don’t use it for backups unless the files you’re sending across the network have already been encrypted, or your session is protected with a VPN connection.) Amazon.com’s S3 (Simple Storage Service) also provides inexpensive, secure file storage on Amazon.com’s servers. But in order to actually get at your storage space, you need to use special software that knows how to communicate directly with S3. A few Mac backup applications can do exactly that. If you want to use a backup program that doesn’t support S3 directly, you may be able to run Jungle Disk (which can mount S3 storage space as a network volume) and then instruct your backup program to use the virtual S3 drive as a destination. In addition, numerous online storage and backup services have proprietary systems that can be accessed only with their own software.

Client-Server: In this table, when I say “Client-Server,” I mean the following: You install a program (the backup server) on a computer on your local network, and then you install another program (the backup client—which in some cases is identical to the server software) on your other computers. The clients connect to the server without requiring that any volumes be mounted in the Finder on either end, and all files are backed up onto a drive attached to the server. Only a few of the programs listed here function in this type of client-server mode, though many of them can back up files over a network in other ways.

Peer-to-Peer: Meet Ann and Bob. Ann backs up her files over the network (local or remote) onto a drive attached to Bob's computer, while Bob backs up his files over the network onto a drive attached to Ann’s computer. This sort of arrangement is called peer-to-peer or mutual backups. Although many programs can be coaxed into producing this end result, a few are explicitly designed to do this easily, without requiring separate client and server software or complicated configurations on each computer.