Gordon,

Sorry, but /boot, /var and /tmp do _not_ have to be on the root file system.
Mine aren't.  Unless you play some games, /bin, /dev, /etc, /lib, and /sbin
have to be part of the root file system.  Anything else can be easily put on
a different one.

~ > df
Filesystem           1k-blocks      Used Available Use% Mounted on
/dev/dasdb1              52284     35868     13720  72% /
/dev/dasdc1            1062992    388560    620436  39% /tmp
/dev/dasdd1            1417324   1337424      7904  99% /usr
/dev/dasde1             111572     50520     55296  48% /var
/dev/dasdf1             104596     73036     26164  74% /opt
/dev/dasdg1              10432      1756      8140  18% /boot
/dev/dasdh1              52284      4936     44652  10% /root
/dev/dasdi1              24384     12912     10216  56% /home
/dev/dasdj1             921228    773876    100556  89% /usr/src

Mark Post

-----Original Message-----
From: Wolfe, Gordon W [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, March 12, 2002 6:45 PM
To: [EMAIL PROTECTED]
Subject: Re: R/O Linux guest?


Part of the problem you will encounter is that Linux needs certain
directories available at boot time before /etc/fstab mounts any other disks.
These include, but are not necessarily limited to:

/boot
/sbin
/bin
/etc
/var
/tmp

In other words, all of these have to be on the boot volume at boot time.
/var and /tmp have to be r/w and the others can be r/o, but since they're
all on the same disk it's best to just make everyting r/w.  At boot time, a
small amount of memory is needed until the swap device is mounted.  After
things have booted to the point where /etc/fstab is read and the new mount
points are mounted, then you can add things into it like

/usr            (most of the dasd space used in Linux/390 is here.)
/home
/opt

We give each Linux instance its own boot disk, dasdb (500 cylinders of
3390-3), and use swap in V-disk (dasda).  then we mount /usr shared
read-only as dasdc (3338 cylinders) and each Linux gets its own /home
read/write as dasdd (or more with LVM), sized to the particular user's
needs.  We're currently experimenting with different shared read-only /opt
disks depending on if the user needs db2, websphere, oracle (beta-test
version) and the like.

Don't get too fancy with multiple disks or it'll end up being a management
nightmare.  Just making /usr shared r/o is problem enough.  Some users want
to update /usr by adding their own .rpm's, but the rpm databases are in
nonshared /var/lib/rpm.

If you want to know what's using the disk space in your system, cd to /
and type the command

du --max-depth=1 -h


"You do not need a parachute to skydive.  You only need a parachute to
skydive twice."  -Motto of the Darwin Society
Gordon W. Wolfe, Ph.D.  (425) 865-5940
VM Technical Services, The Boeing Company


> ----------
> From:         Arty Ecock
> Reply To:     Linux on 390 Port
> Sent:         Tuesday, March 12, 2002 12:15 PM
> To:   [EMAIL PROTECTED]
> Subject:      R/O Linux guest?
>
> Hi,
>
>    I need to set up a Linux/390 guest with read-only file systems (and
> minidisks).  Has anyone done anything like this?  I'd want to put the
> portions of the file systems that MUST be read-write on a V-disk.
>
>    My filesystems are all on separate minidisks:
>
>    /
>    /home
>    /usr
>    /opt
>    /tmp
>    /var
>    swap
>
>    I think I can make /usr, and /home read-only rather easily.  The same
> with /opt.  For the others, I'd have to disect them to locate the files
> that must be read-write and set up symlinks for them.  Am I on the right
> track?
>
> Cheers,
> Arty
>
>

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