----- Original Message -----
From: mrweb <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Saturday, December 16, 2000 9:41 PM
Subject: Re:[expert]fstab for 3 OS's


> Hi List,
>
> Many thanks to Rusty and Anthony. :)
>
> I learned that in order to have a multi boot system the way I
> had asked, would require me to appropriately edit each of my fstabs in
> all of my systems and also my boot loaders(?), if I wanted to be able
> to boot all of them from each other.
>
> I didn't quite follow the `mount point' portions? Which leads me to
> another question or two.
>
> For simplification, so I thought, I had asked in reference to 3 OS's.
>
> What I really want is to have access to my files in all of my OS's
> from my Primary OS, this requires me to have the ability to mount
> each OS from my Primary OS.<--- This I thought was just a matter of
> editing my Primary fstab?
>
> I was thinking that to be able to boot all of my OS's from a system reboot
> would only require editing my grub.conf, after the editing of my fstab(s),
> to show that they all existed and to give them an order of preference,
> and a mount point.
>
> All of the information I have read on this subjuect always deals
> with 'DUAL BOOT' machines only, never a mention of 3 or more systems
> needing to be booted. Which has been a wee bit frustrating at times.
>
> I have a 5 OS's on my machine, my hard drive looks like this;
>
> +----------------------------------------+
> |windows|LM 7.0|LM 7.1|swap|debian|LM 7.1|
> |hda1   |hda5  |hda6  |hda7|hda8  |hda9  |
> +----------------------------------------+
>
> only one of which is my `Primary OS', and it is mainly this one, from
> which I wish to have desktop access to the others, just as I do to
> `windows', although it would be great to be able to boot each OS from grub
> after a reboot.
>
> Where I am getting hung up, is on the `mount points', as ALL of my Linux
> OS's have a mount point of `/'. Perhaps I should have built them in a
> different way, but that's how I did it.
>
> :(
>
> Currently if I do a reboot, Grub comes up and I have the option to boot
> into my Primary OS (hda9) or into windows, if I want to boot any of my
> other Linux Systems I insert the appropriate boot floppy and away I go.
> This is a bit of a pain, but it is not really a BIG concern although it
> would be good to have all of my systems, available to boot from Grub.
>
> Thanks,
>
> mrweb
>
>
>
>


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Hi. Let me see if this helps:
Let's simplify this situation a little bit, by looking at my filesystem. My
machine has two OS's. On my first partition, I keep Windows 98. However, my
primary operating system is Linux. (It wouldn't matter if it were Windows,
because Windows doesn't allow you to read and write Unix filesystems
directly). I am to boot my Linux operating system, and access my Windows
partition.

I have my Windows partition "mounted" in my Linux file system under the
directory /.  That is to say, that in my fstab file, I have an entry like
this:

    /dev/hda1        /c        vfat    user,exec,umask=0        0    0

This means that when I boot Linux and want to read from my windows
partition, it is found in the directory under / called c. So I can just 'cd
/c' to reach the C:\ drive of Windows. It's just not called that in Linux.
If I wanted, I could have "mounted" the windows C:\ drive under
"/mnt/exchange" so that if I said 'cd /mnt/exchange' it would give me the
'file folder' that contains the C:\ directory from Windows. Mounting
something into the file system essentially tells Linux where to place that
resource in the file structure. With Linux, you have absolute freedom to
place it wherever you want.  :-)

A very informative source of information about the fstab file is found my
executing a 'man fstab' command from a shell prompt in a terminal. To make a
long story short, you could have three OS's on your machine. Each one
(unless one is Windows), will have an fstab file. If you have three (or
five) distinct operating systems, one of which is Windows, then presumably
you have five distinct file systems. Each of the file systems can be reached
(or not) by any of the Linux OS's.

This is done by having an fstab file with entries to mount each of the file
systems under the file system for the current operating system. This is done
for each file system. For example, let's say you wanted your third
partition's LM7.1 to be your 'primary' operating system. In the partition
holding that operating system (hda6) you will have a / directory. Under that
directory, will be a folder named etc/. Under etc/ will be a file named
fstab that must contain the following entries (or something similar):

    /dev/hda6        /        ext2      defaults      1    1
    /dev/hda1        /win   vfat        user,sync,auto,asynch,atime        1
2
    /dev/hda5        /alt0    ext2    defaults        1    2
    /dev/hda7        swap    swap    defaults    0    0
    /dev/hda8        /deb    ext2    defaults        1    2
    /dev/hda9        /alt1    ext2    defaults        1    2
    /mnt/floppy     /mnt/floppy    auto    defaults    0    0
    /mnt/cdrom     /mnt/cdrom    iso9660    defaults    0    0

This depends upon some other factors: Does your kernel support the 'auto'
fstype?, maybe otherfactors. You will need to add the directories 'win',
'alt0', 'alt1', and 'deb' under the root ( / ) directory by cd'ing to the /
directory and then using:

     mkdir [place the name of the directory here without the brackets]

What this fstab says is that for this Linux, the devices in the first column
are mounted at the location shown in the second column.  The filesystem type
is the type listed in the third column (vfat, ext2, auto, iso9660). If your
kernel doesn't support auto, and you don't wish to compile a new kernel at
this time, then vfat is usually a good choice for the floppy drive. This
will cause problems, however, if you attempt to use a different type of
floppy disk. like a linux native disk (ext2). The fourth column is called
options, and you may look up options by typing 'an 8 mount' (without
quotes).

Each OS will have its own /, that is true.  Grub tells the computer which
root belongs to the particular OS when it boots it. You need to provide that
information to grub, however. I will not be able to do this procedure
justice in this forum. If you have grub currently installed on your system,
and at least one of your Linux's boots, then there is a fine explanation of
everything you need to know in the 'info grub' entry. Type 'info grub'
(minus the quotes) and use the space bar to proceed to the next page, and
backspace to return to a previous page. If you can't do this, contact me.

PS: you will need to provide a suitable fstab file for each operating
system. The root ( / ) file system will be designated for a different device
number in each operating system. For example, in the file I showed you, it
was designated for /dev/hda6. For the next one, / would be listed in the
second column after /dev/hda5, and the line with hda6 would have a name like
/main listed (don't forget to create this directory under the root of the
current filesystem). Each new filesystem will require you to create all of
the directories that you specify for the alternate partitions, ie, the
filesystems for the other OS's. To make a certain filesystem invisible to a
certain OS, enter 'ignore' (without quotes) as the type (instead of vfat,
ext2, etc).

PPS: Another option would be to just have two filesystems (one of which is
windows), one fstab file, and have Grub just give you options for which file
to use as the current kernel. This would make your entire Linux filesystem
available to all of your incarnations of Linux. This may cause problems with
libraries, however. I'm not sure.

I hope that all this helps. It is entirely possible that I have taken some
step for granted, or that I have overlooked something, or even that I don't
understand your question. Please feel free to respond, and I will do my best
to assist you.

Good Luck,
Rich Chase


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