Silverkeeper and Windows servers

Last summer, I searched for a free, OS X network backup utility. I want free, so that we may easily adopt it here at school without additional costs or licensing bureaucracy.

A teacher today alerted me to the fact that Silverkeeper was not overwriting existing files with newer versions as it should. In other words, if you created a file and then updated it later, Silverkeeper would not copy over the updated version. Problem!

I wrote LaCie and received the following reply:

Network shares are a problem due to how OS X deals with dual fork files that Mac OS Extended file system relies on – if network connection does not fully support the Mac file system, you end up with two files on the network share for each native file on the Mac computer. One hidden with file permission/privilege and other info; one visible file with file data.

Therefore, unless you understand the limitations of your network connection, you should not rely on SilverKeeper for this type of backup.

Instead, as a workaround, you can use sparse disc images located on the network share and mounted locally to the Mac running SilverKeeper. This method assures a proper Mac OS Extended formatted Destiantion that fully supports the Mac file system. this is briefly mentioned in the release notes located inside the SilverKeeper application folder.

the alternative is to use a backup program that makes proprietary backup archives.

I still don’t understand why an invisible permissions file would prevent Silverkeeper from determining that the copy on the server is older and overwriting it. Nonetheless, LaCie acknowledges that this is a known problem, and I cast off for a new solution.

PSyncX: Has something changed in Leopard? It could not find “make” on my computer to compile the Perl file copy library it uses.

iBackup: I am trying this now. Looks good so far.

These two sites were most informative:
Complete, free Mac backup
Mac Backup Software Harmful

3 comments

  1. Ben Chun says:

    Time machine — do it!!

  2. rkassissieh says:

    Time Machine doesn’t back up to network volumes, only hard drives. Also, I would wait until Time Machine proves its reliability before entrusting all of your data to it.

  3. Ben Chun says:

    What is Time Capsule if not a Time Machine backup over the network? A quick search reveals that you can indeed do this without Apple’s hardware: http://andreas.louca.org/20

    It also looks like there are some caveats, and of course with any backup plan it’s not done until you’ve tested it and can restore from it. Test test test!!