romkey@ASYLUM.SF.CA.US (John Romkey) (10/16/90)
Yes, Geoff is right about RVD. It was actually originally done to allow LCS to have its many VAX 750's (each complete with about 28MB of disk) to share filesystems on a disk server. Each fileserver had several RA81's, later to be replaced by Fujitsu Eagles, which had a lower failure rate (the 6 RA81's were replaced about 14 times in 12 months - this was quite a few years ago). RVD actually dedicated entire UNIX partitions of the physical disk to the server, so you didn't have the extra overheard of going through the UNIX filesystem. A disk could have multiple readers, one writer or multiple writers. The idea was that if there were multiple writers there would be an extra protocol used among the writers to synchronize them. I don't believe this ever got done. As a hack, we wrote an RVD driver for DOS. Then people could share a common DOS filesystem with binaries and things on it, and also have private ones so it didn't matter if they didn't have a hard drive. I don't think it ever made it into a public PC/IP distribution, though several people got private copies. Doing this required some changes to PC/IP so that you could run both RVD and a PC/IP application (each had its own linked in driver and protocol stack). It was done by having some conventions in the code about (1) not accessing the RVD drives from PC/IP programs and (2) trying to have the PC/IP programs always leave the network card in the same state they found it in. This was in the days before we had TCP/IP TSRs. Anyway, it worked, it was pretty slow, and the model of communication really was at a disk level, not a filesystem level, so you couldn't *really* share the filesystem the way you'd like to. I don't know of anyone who uses RVD now, I don't know where to even find the specs for it anymore. I'd much rather use NFS myself. - john romkey USENET/UUCP: romkey@asylum.sf.ca.us Internet: romkey@ftp.com
bkc@omnigate.clarkson.edu (Brad Clements) (10/16/90)
Clarkson used RVD for a year to network public PCs to a disk server. We used our MVaxII as a server, a specially hacked packet driver multiplexor (not recommended for the faint of heart) and a special custom config.sys driver that allowed the RVD disk functions to be loaded as a TSR rather than all in the device driver. This combined with our BootP eprom for booting diskless PCs gave us a fair imitation of a LAN. This setup was quite fun, except when it came time to update the files on the disks (once a day in some cases), thats when all users had to be kicked off the 'system'. After much grumbling from the users, and lots of timeouts (the protocol wasn't very robust), we finally moved to Novell (probably should have done this in the first place, after a cost analysis). Anyway, it was fun. | Brad Clements bkc@omnigate.clarkson.edu bkc@clutx.bitnet | Sr. Network Engineer Clarkson University (315)268-2292
romkey@asylum.sf.ca.us (John Romkey) (10/17/90)
By the way, RVD is not available for distibrution. It hasn't been in use at MIT for years, so by now it would've suffered a lot of bitrot. I wouldn't be surprised if the sources for it didn't exist anymore. I don't recall it ever being released publically, and it's probably not what you should really be running... - john
nelson@sun.soe.clarkson.edu (Russ Nelson) (10/18/90)
In article <9010161443.AA19891@asylum.sf.ca.us> romkey@asylum.sf.ca.us (John Romkey) writes:
By the way, RVD is not available for distibrution. It hasn't been in
use at MIT for years, so by now it would've suffered a lot of bitrot.
I wouldn't be surprised if the sources for it didn't exist anymore. I
don't recall it ever being released publically, and it's probably not
what you should really be running...
What's wrong with RVD? I've got two PCs, one at work, and one at
home. I'd to run a little TSR program that acts as a RVD server on
each machine, and also a RVD client, so that my D: drive would be my
"other" machine. I don't mind at all if I only get read access to the
other machine. It seems like RVD would be the perfect protocol to
use.
--
--russ (nelson@clutx [.bitnet | .clarkson.edu]) Russ.Nelson@$315.268.6667
It's better to get mugged than to live a life of fear -- Freeman Dysonromkey@ASYLUM.SF.CA.US (John Romkey) (10/19/90)
I said "it's probably not what you should really be running", and I stand by that statement. I believe RVD doesn't provide the type of service most users will want. - john romkey USENET/UUCP: romkey@asylum.sf.ca.us Internet: romkey@ftp.com