MacOS X: Backup and Restore Entire Volume

dankogai@dan.co.jp

TIGER USERS

/usr/bin/rsync that comes with Mac OS X v10.4 (Tiger) now supports resource fork operation with -E option. You should consider this an alternative to psync.

Overview

Until MacOS 9.x, MacOS is the easiest platform to do full volume backup. All you have to do is grab a media large enough and drag the target hard drive icon to destination drive. When you restore the volume,just select the destination drive via "Startup Disk".

That is no longer the truth with MacOS X. As hyped very loudly MacOS X is a "moisturized" BSD Unix which requires proper files located at proper path. Unlike MacOS 9 where the only folder required to boot a volume is "System Folder" which path can be anywhere in the volume, MacOS X requires such folders as /etc and /usr directly under the startup volume. To make matters further complicated, MacOS X Finder ("Aqua Finder" as follows) hides these critical folders, disabling attempts to restore volume within Aqua Finder.

Then how about good old Unix method? dump/restore? tar? dd? rsync? To a good old unix user, the command below appears to work;

cd /; tar -Xcf - . | (chdir /Volumes/dst && tar -xvpf -)

Sorry, it does not. MacOS X is too moisturized to apply straight unix methods. MacOS X appears to be dependent on HFS(+) file attributes which are rendered inaccessible from those conventional unix commands. So what you get is a volume stripped with all resource forks and finder attributes.

So what are you going to do? Here it is.

Single-command solution: psync

In hope to remedy this situation, I have written psync, a perl script that comes with MacOSX::File.

Due to its popularity it now has its own page.

Backup and restore via MacOS 9

This section is now in a separate document.

FAQ

Q: Why can't you use Aqua Finder to backup?

A: Give it a try. You will find you can't copy files due to insufficient permission. We need Classic Finder to forciblly ignore permissons.

Q: MacOS 9.x ignores file permisson. Then why does the copy via Classic Finder works?

A: Because Classic Finder copies all HFS+ attributes, including such attributes as file permissions and ownershipsthat are not used by MacOS 9.x

Q: Can't you use CpMac utility for that purpose, say "cd /; CpMac -r Applications Library .. /Volumes/to_volume" ?

A: Sorry. While CpMac copies resource fork and other attributes, it resets file ownerships and modification dates. As a result, the system gets clobbered. Trust me, I've already done that.

Q: Is there any way to incrementally back up MacOS X volumes?

A: psync discussed above does just that!

Q: This is still too complicated to me! Easier solution, please!

A:See "Alternatives" below.

Alternatives

As Larry Wall says, there are more than one way to do it. Here is some.

• Allan Marcus told me in response to this page that Apple Software Restore 2.1.1 (ASR) or later can be used. He also mentioned, however, that ASR is not available online so you need to have a fairly recent Macs.
• Josh Wood reported that a command /usr/bin/ditto may be used. This solution is discussed thoroughly in MacOS X: /usr/bin/ditto and backup. Ditto-based solution is also discussed in this article by Mike Bombich
• As mentioned above, Danz Retrospect is now available.
• If you are looking for a free, GUI-based solution, try Synk 4. However, the help file clearly states as follow;
  
  What Synk Cannot Do

  Synk will not mirror one hard drive to another. It was designed to copy your home directory or any other folder to another location, not create a bootable backup.

  Synk cannot copy symbolic links over an Appleshare network. They are converted by the network client into normal files. This will not affect most Macintosh users.

  Synk cannot synchronize between HFS+ and foreign file systems because the directories are sorted differently. Make sure the volumes you are copying between are both formatted in the extended HFS+ format.

• Apple itself has released a utility called backup, which works with your .Mac account. Of course, .Mac disk is definitely not a place to backup entire boot volume but should be enough to backup your home directory.
• dd command should work if the target volume is EXACTLY the same size as source volume.
• OpenDarwin now offers rsync_hfs. As of this writing it's avaliable via CVS but this is definitely the solution people like myself wanted (I might not have developed psync if that were available).

History of this Document

2002.10.20

psyncnow has its own page.

"Alternative" section completely revised.

2002.03.05

Rewritten with stylesheet; Validated with W3C HTML Validator

Binary distribution of MacOSX::File introduced

2002.01.19

Rewritten in great deal to introduce psync

2001.07.03

More typos fixed (thank you, Struan Robertson, et al.).

2001.07.01

Alternatives section added.

ditto-based solution is added.

2001.06.29

Updated in response to feedbacks(Thank you, Gary L. Gray and others responded)

2001.06.28

Introduced in "MacFixit: Troubleshooting for MacOS X"

2001.06.14

Created & Uploaded