wallen@sdics.UUCP (Mark Wallen) (10/16/86)
When one runs NFS, there are some additional interesting things that seem to become possible. For instance, you could really run dual ported disks between two systems. The old bugaboo with dual porting your drives was that only one port could be read/write, so that you didn't completely scramble your disk. And moreover, when lots of in core caching of disk data was done (like UNIX likes to), the readonly port still gets only an inconsistent view of the disk. In the brave new world of NFS, you would have your read/write port as usual, but the second system mounts the disk as a NFS partition from the read/write host. So far you have bought nothing; but when the NFS server crashes then you umount the NFS partition and mount the file system (perhaps an fsck would be prudent :-) on the second system. With clever software, the original NFS server would become the client when it came back up! Also, it seems as though it would be possible to build a "left handed" NFS server. That is, one that read up a remote/foreign file system (byte swap, etc) from a local disk. Thus, one should be able to use different hosts (e.g., sun and vax) to implement the dual port scheme above. (Of course, you probably also want a left hand fsck and dump). Has anyone else thought of this (and found the holes)? Anyone actually done it? Mark Wallen Institute for Cognitive Science UC San Diego ucbvax!sdcsvax!sdics!wallen.uucp wallen@ucsd.edu wallen@nprdc.arpa