The state of backup and cloning tools under Mac OS X¶

Back in the days of OS 9, making DVD copy files for Mac was fairly easy. Unfortunately, the simplicity is gone with OS X. Such a simple approach is no longer a guarantee to preserve all data faithfully. The trouble on OS X is mostly related to metadata. i.e., data about files and directories. Another problem arises when a complete system partition shall be backed up and be bootable later on. Making a backup bootable is not trivial. Seemingly one could nourish high expectations about the state of backup solutions on Mac OS X. However, the fly in the ointment is that these tools are generally not aware of Mac OS X metadata and, hence, fail to produce a faithful backup.

This essay will investigate means to make DVD copy files for Mac as completely and reliably as possible on Mac OS X. The tools covered are not only relevant for backup purposes, but also for the case of migrating machines, when the content of one hard drive is to be cloned to another. The analysis presented here assumes a recent install of OS X 10.4.5 (Tiger) with all updates. Making a DVD copy file for Mac and being sure that all information has been copied is not easy under Mac OS X. Nevertheless, achieving this goal is obviously paramount for backup purposes. There is one main culprit for all issues: metadata. Different operating systems have traditionally supported a wide range of metadata, with many headaches in cross-platform environments stemming from differences in metadata support. Mac OS traditionally supported rich metadata compared with other operating systems. The following are depictions about what categories of metadata the corresponding tools preserve Apple (10.4.6) preserves cp-Rp, Finder, ditto and rsnyc-aE. Apple (10.4.5) preserves ASR (dev mode) and ASR (file mode). Apple preserves CpMac-r-p.

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The state of backup and cloning tools under Mac OS X¶