Thanks for your hints. On closer examination, I found that my auto start problem is bundle specific.
For my OSGi environment to work, I have to start 4 bundles:
org.eclipse.equinox.cm, javax.persistence, org.eclipse.persistence.jpa.osgi and org.eclipse.equinox.ds.
I can start the first three bundles via the site's startPlugin element using their bundle ids, regardless of their location.
org.eclipse.equinox.ds however generally requires a more specific location argument like osginsf:dots/updatesite-lib.nsf/8C0A3CDBDDEE2866C125790D002D15E3/org.eclipse.equinox.ds_1.2.1.r36x_v20100803.jar or ../../../updatesites/lib/eclipse/plugins/org.eclipse.equinox.ds.
The only way to get this bundle started by its bundle id ist to place it in the primary osgi directory (${dominobin}\osgi-dots\rcp\eclipse\plugins).
I have no idea why this bundle behaves different than the other ones. I get no error messages, and after a failing startup the bundle is reported as resolved and can get started manually.
This happens on Windows XP and linux. I tried both Eclipse 3.6.2 and the recommended 3.5.1 version as the DOTS environment. I used the org.eclipse.equinox.ds version 1.2.1.R36x_v20100803 and 1.0.0.v20080427-0830.
I am attaching a typical startup log that states that the bundle cannot be found (no big surprise).
Do you have any idea what might go wrong here?