Technical Note FL505

Alias Manager Q&As

CONTENTS Volumes must have unique creation dates Downloadables

This Technical Note contains a collection of archived Q&As relating to a specific topic--questions sent the Developer Support Center (DSC) along with answers from the DSC engineers. Current Q&As can be found on the Macintosh Technical Q&As web site. [Apr 01 1991]

Volumes must have unique creation dates

Date Written: 3/16/92

Last reviewed: 6/14/93

Sometimes the Alias Manager mistakes one volume for another. In particular, we're experiencing problems getting aliases to volumes to work correctly with our AppleTalk Filing Protocol (AFP) server volumes. Here's how I can duplicate the problem:

1. I mount two server volumes from my AFP server: VolA and VolB.
2. I use the Finder to create an alias file for each volume.
3. I unmount VolA.
4. I open the alias file for VolA. However, when I do this, VolB (which is still mounted) is opened.

Is this a bug in the Alias Manager or did we implement something the wrong way in our server?

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As noted in the Alias Manager chapter of Inside Macintosh Volume VI, the Alias Manager uses three criteria to identify a volume: the volume's name, the volume's creation date, and the volume's type. If the Alias Manager can't find a mounted volume that matches all three criteria, it tries again with just the volume's creation date and the volume's type. This second attempt finds volumes that have been renamed. If that attempt fails, the Alias Manager tries one last time on mounted volumes with the volume's name and the volume's type. If it can't find a mounted volume with those three attempts and the alias is to an AFP volume (a file server), the Alias Manager assumes the volume is unmounted and attempts to mount it.

The problem you're having is probably happening because both volumes have the same creation date and type. That will cause the Alias Manager to mistake VolA for VolB and VolB for VolA when it attempts to match by volume creation date and volume type. You can prevent the Alias Manager from making this mistake by making sure your server volumes all have unique volume creation dates.

This same behavior can be observed when partitioned hard disks use the same volume creation date for all partitions. If one partition isn't mounted, the Alias Manager can mistake one disk partition for another.

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