I'm looking for an open source spatial file server to house and serve my GIS data. I'm currently using my Ubuntu Server as a ssh file server and have to download the data to the local computer, manipulate and then re-upload to the server. I would prefer to use ArcCatalog to connect to the server and manipulate the data in-situ. Are there any open source Spatial servers that Arc will communicate with? I'm not very interested in WMS or other web based displays.
If all you need is a file server, not a spatial database server, the simplest way is to just install samba, share a directory via /etc/samba/smb.conf (or use a gui if you don't need anything complicated like active directory integration) and map that directory as a network drive in Windows Explorer.
For my own work, I use a Postgres server with PostGIS extensions. I personally like it because of the new RASTER support that was built into PostGIS v2.
Here are some resources that might help you:
http://www.postgis.us (The book "PostGIS in Action" is excellent)