glenm@tekecs.UUCP (Glen McCluskey) (10/09/85)
Is it possible to have UNIX and VMS coresident on the same physical disks? I don't mean running at the same time, just the ability to switch back and forth without changing disk packs. Glen McCluskey ..tektronix!tekecs!glenm
fair@ucbarpa.berkeley.edu (Erik E. Fair) (10/10/85)
In article <5732@tekecs.UUCP> glenm@tekecs.UUCP (Glen McCluskey) writes: > >Is it possible to have UNIX and VMS coresident on >the same physical disks? I don't mean running at >the same time, just the ability to switch back and >forth without changing disk packs. It should be possible to do this, provided that you can make sure that UNIX does not tamper with the VMS partitions of the disk, and that VMS does not tamper with the UNIX partitions of the disk. I know this is doable with UNIX. A VMS wizard will have to answer as to whether VMS can do this. Erik E. Fair ucbvax!fair fair@ucbarpa.BERKELEY.EDU
rcb@rti-sel.UUCP (Random) (10/11/85)
In article <10605@ucbvax.ARPA> fair@ucbarpa.berkeley.edu (Erik E. Fair) writes: >In article <5732@tekecs.UUCP> glenm@tekecs.UUCP (Glen McCluskey) writes: >> >>Is it possible to have UNIX and VMS coresident on >>the same physical disks? I don't mean running at >>the same time, just the ability to switch back and >>forth without changing disk packs. > >It should be possible to do this, provided that you can make sure that >UNIX does not tamper with the VMS partitions of the disk, and that VMS >does not tamper with the UNIX partitions of the disk. I know this is >doable with UNIX. A VMS wizard will have to answer as to whether VMS >can do this. > If UNIX can be made to boot from anywhere on the disk, this can be done. If the UNIX can be modified to not require any special physical blocks on the disk, all you need to do is create the disk as a VMS disk, create a hugh file (half the disk) and place the unix in this file. When vms is running, it will be just a file and will be left alone. When unix is running, it will be thought of as the entire disk and the other parts will be left alone. Be sure that this file created on VMS is contiguous! That takes care of the VMS side. Back in your court UNIX wizards. Can UNIX be modified as I described. -- Random Research Triangle Institute ...!mcnc!rti-sel!rcb
roy@phri.UUCP (Roy Smith) (10/12/85)
> >Is it possible to have UNIX and VMS coresident on the same physical disks? > > It should be possible to do this, provided [...] UNIX does not tamper with > the VMS partitions of the disk, and that VMS does not tamper with the UNIX > partitions of the disk. I remember an example of a program which was both legal Pascal and legal C (in SIGPLAN notices, I think). The trick, of course, was to hide the C code inside of Pascal comments, and the Pascal code inside of C comments, sharing code whenever compatible syntax made that possible. Any dual Unix/VMS wizard (do such creatures exist?) want to try building a disk which has both a valid Unix and a valid VMS file system *on the same partition*? To be fair, both file systems can be read only. Presumably you would hide the Unix inodes and directories in the VMS data files and vice versa (I know VMS doesn't have inodes, but it must have something like them). Competition for the lowest numbered physical blocks (boot block, Unix super block, free list, etc) would be the real tough part. Brownie points if the two file systems contain the same text file using the same physical data blocks. Talk about portability; imagine using the same file system image to distribute software to both Unix and VMS sites! -- Roy Smith <allegra!phri!roy> System Administrator, Public Health Research Institute 455 First Avenue, New York, NY 10016
mwm@ucbopal.BERKELEY.EDU (Mike (I'll be mellow when I'm dead) Meyer) (10/15/85)
In article <522@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: >> >Is it possible to have UNIX and VMS coresident on the same physical disks? >> >> It should be possible to do this, provided [...] UNIX does not tamper with >> the VMS partitions of the disk, and that VMS does not tamper with the UNIX >> partitions of the disk. > > Any dual Unix/VMS wizard (do such creatures exist?) I've known a few people who were just sub-wizard on both, so i expect that they do. >want to try >building a disk which has both a valid Unix and a valid VMS file system *on >the same partition*? To be fair, both file systems can be read only. Sorry, no can do. VMS doesn't grok "partitions." A disk is a disk is a disk, and you have to deal with the whole thing at once. As has been pointed out here, you *can* allocate a large chunk of the disk as a contigous file on VMS. You then make your Unix partitions all live in that file. The only problem left is what to install as the boot block on the disk. I'm not familiar with the VMS boot sequence, so I'd be tempted to put the Unix boot sequence in, with a file (/vms) that you boot to bring up VMS. Of course, since VMS can easily get to the Unix half of the disk, it might be easier to do things the other way around. <mike
pdg@ihdev.UUCP (P. D. Guthrie) (10/15/85)
In article <91@ucbjade.BERKELEY.EDU> mwm@ucbopal.UUCP (Mike (I'll be mellow when I'm dead) Meyer) writes: >In article <522@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: >>> >Is it possible to have UNIX and VMS coresident on the same physical disks? >>> >>> It should be possible to do this, provided [...] UNIX does not tamper with >>> the VMS partitions of the disk, and that VMS does not tamper with the UNIX >>> partitions of the disk. >> >> Any dual Unix/VMS wizard (do such creatures exist?) > >I've known a few people who were just sub-wizard on both, so i expect that >they do. > >>want to try >>building a disk which has both a valid Unix and a valid VMS file system *on >>the same partition*? To be fair, both file systems can be read only. > >Sorry, no can do. VMS doesn't grok "partitions." A disk is a disk is a disk, >and you have to deal with the whole thing at once. > Yes, but isn't it possible to write device drivers for Vmess that use different disk formats? I'm sure that it must be (I don't know Vmess). You could then get some type of device (I think SI does this) that makes one large disk look like a bunch of smaller disks and format some unix and some VMS. The uVax I think requires this for the larger capacity drives. I also remember something about a SI controller that lets two uVaxen use the same disk, so it might be possible to have one run VMS and one Unix, and access each other's data through partitions (virtual disks) handled by the controller. >As has been pointed out here, you *can* allocate a large chunk of the disk >as a contigous file on VMS. You then make your Unix partitions all live in >that file. > >The only problem left is what to install as the boot block on the disk. >I'm not familiar with the VMS boot sequence, so I'd be tempted to put the >Unix boot sequence in, with a file (/vms) that you boot to bring up VMS. Of >course, since VMS can easily get to the Unix half of the disk, it might be >easier to do things the other way around. > > <mike
weltyrp@rpics.UUCP (Richard Welty) (10/22/85)
> In article <5732@tekecs.UUCP> glenm@tekecs.UUCP (Glen McCluskey) writes: > > > >Is it possible to have UNIX and VMS coresident on > >the same physical disks? I don't mean running at > >the same time, just the ability to switch back and > >forth without changing disk packs. > > It should be possible to do this, provided that you can make sure that > UNIX does not tamper with the VMS partitions of the disk, and that VMS > does not tamper with the UNIX partitions of the disk. I know this is > doable with UNIX. A VMS wizard will have to answer as to whether VMS > can do this. > > Erik E. Fair ucbvax!fair fair@ucbarpa.BERKELEY.EDU To the best of my knowledge, VMS is quite unable to deal with partitions of a disk ... every VMS system I've ever seen treats the whole disk as a single collection of disk blocks. -- Rich Welty (I am both a part-time grad student at RPI and a full-time employee of a local CAE firm, and opinions expressed herein have nothing to do with anything at all) CSNet: weltyrp@rpi ArpaNet: weltyrp.rpi@csnet-relay UUCP: seismo!rpics!weltyrp
tihor@acf4.UUCP (Stephen Tihor) (10/22/85)
Note that the primary VAX bootstrap code (VMB.EXE) can be made to load an arbitrary thing from an arbitrary block and then branch to it. Thus putting a FILES-11 structure on the disk as the basic file structure and restricting UNIX to a partition that was a large suitably inaccessible file (or bad block list) to VMS sould suffice admirably. Fortunately for UNIX's generality the PDPism that restricted the number of i-nodes on a disk forced it to develop virtual disks (aka partitions) as the standard way of handling almost all disks in current use and even Berkeley has not felt impelled to replace them.