Chang Song offered some additional information on V4.0X and V5 file system
compatibility which may be useful to others on the list, so I thought I'd
post his comments on Dr. Tom's answer.
Frank
----- Original Message -----
From: "Chang Song" <song_at_zk3.dec.com>
To: "Frank Wortner" <frank_at_kang.bondnet.com>
Sent: Friday, April 06, 2001 12:43 PM
Subject: Re: SUMMARY: Multiple OS Versions on One Disk
> Frank Wortner wrote:
> >
> > A number of you wrote replies on this topic, but as usual, Dr. Tom
Blinn
> > had the best answer. (That man deserves some sort of medal!) I've
> > reproduced it below. Thanks also to Trevor Osatchuk, Alan from DEC
> > (Compaq), Ivan Hoe, Alan Davis, and Chang Song. If I've left anyone
out,
> > my apologies. (I was experimenting with new IMAP server software using
my
> > own email spool and might have lost some messages.)
> >
> > Frank
> >
> > > Yes and no.
> > >
> > > In general, you can re-use one swap partition for all the releases,
but
> > > be careful about rebooting a different version after a panic (the
other
> > > version may not know what to do with the crash dump that will be in
the
> > > swap partition), and be aware that the way you identify the swap area
> > > is different between V4.x and V5.x.
>
> Well they are not different. You can still specify swap partition in
/etc/fstab
> in V5 and V4. Just that you can now specify swap area in /etc/sysconfigtab
> in V5
>
>
> > > In general, a newer release can mount read/write the file systems that
> > > were created by an older release. The reverse may not be true. UFS
is
> > > the universal file system format, and if you stick to UFS, you likely
> > > will have no problems, but if you want to set up a V5.x TruCluster you
> > > MUST use AdvFS, and in V5.1 there is a new on-disk AdvFS format that
> > > is NOT understood by the older releases. That is, if you create a new
> > > AdvFS domain in V5.1, you will NOT be able to access it from V4.x or,
> > > I believe, V5.0 or V5.0A.
>
> If you create Advfs Domain V 3 in V5.1, you can share it with V4.x.
> Default domain in V5.x is Version 4.
>
>
> As I told you earlier, there are two UFS version as well. v.3 (that
> can be used in all release) and v.4 (that supports 64k hardlinks
> but can only be used v5.0 and later).
>
> But as long as hardlink doesn't go over 32767, you can use the UFS
> partition in all releases.
>
>
> > > Also, V5.x introduced the presence of "cluster dependent symbolic
links"
> > > into the file systems, and where these are present in a V5.x file
system
> > > you will need to manually parse them, from the view of a V4.x kernel,
> > > it will just be a symlink that doesn't lead to a file (it will think
> > > the "{memb}" token in the symlink is supposed to be the name of either
> > > a directory or a file or another symlink, and it won't find one unless
> > > you put one at the right place, and if you do that, you'll break your
> > > file system for the V5.x kernels).
>
> Yes this CDSL could be messy in V4.x.
>
> --
>
> Chang Song, UFS, Tru64 UNIX (Chang.Song_at_compaq.com) Work: (603)
884-0799
> Compaq Computer Corp., Mailstop: ZKO3-3/U14 Home: (603)
437-5088
> 110 Spitbrook Rd., Nashua, NH 03062 Cell: (603)
930-5088
Received on Fri Apr 06 2001 - 16:57:14 NZST