On Mon, Jan 25, 2010 at 4:25 PM, keith wrote (on the squeak-dev list) :

> pier keeps its data in image.

I know the following info is unlikely to help your current
application, but, in the interest of completeness, I will observe that
at least one Pier application stores its user data in the host
filesystem, not the image. That application is WikiServer (John
McIntosh's cross-platform personal wiki for the iPhone)

I only have superficial familiarity with Pier and WikiServer:  as far
as I can tell, the persistency code uses MAExternalFileModel, but
sadly I can't guess if the effect is available to all Pier developers,
or proprietary to WikiServer.