Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!ASYLUM.SF.CA.US!romkey From: romkey@ASYLUM.SF.CA.US (John Romkey) Newsgroups: comp.protocols.tcp-ip.ibmpc Subject: re: PD PC-NFS Message-ID: <9010140041.AA17561@asylum.sf.ca.us> Date: 14 Oct 90 07:41:48 GMT References: <251@srchtec.UUCP> Sender: daemon@ucbvax.BERKELEY.EDU Reply-To: romkey@asylum.sf.ca.us Organization: The Internet Lines: 38 Date: 5 Oct 90 14:17:30 GMT From: Michael Almond Organization: search technology, inc. Sender: pcip-request@udel.edu I've heard the term redirector before and assume you mean routines which intercept OS requests to a drive and hand them over to the NFS routines. If this is what you mean by redirector, couldn't you use some ramdisk software as a starting point? No. Ramdisk software for PC's tends to operate by supplying PC-DOS with a new disk driver that reads and writes memory instead of disk. A "redirector" operates differently. It doesn't see disk block requests; it sees file operation requests. Redirectors either grab int 21 and check if the DOS calls are for their network drives or for DOS (passing the request through to DOS in that case), or sit under DOS using the calls through DOS that Microsoft provides so that their redirector can do something similar. I don't believe this interface is documented, but at least one person has successfully reverse engineered it. The problem with writing a redirector is that it's a pain in the ass to mimic the semantics of the DOS filesystem. You have to return all the correct error codes in all the correct situations, deal with the undocumented systrem calls, and in general act like DOS acts. Ick. (BTW, I'm very interested in writing this software. IMHO PC networking software is over priced.) Believe me, once you add in the development costs, the costs associated with tracking the changes in protocol specifications and supporting that new version of DOS or new display card or new network interface, and building up a support organization that can handle calls from users who have problems with other vendors' software, you're spending lots of money... - john romkey USENET/UUCP: romkey@asylum.sf.ca.us Internet: romkey@ftp.com