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, unless you try to mount the partition, UNIX simply doesn't
> care what's in it. So there is no problem having file systems created
> by different version in different partitions on the same disk.
>
> I'm sure you realize you'll need a boot disk for each version, and that
> you are looking to be able to do things like share swap or just get to
> things from a different version.
>
> 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.
>
> 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.
>
> 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).
>
> So, yes, it can be done, but it's messy and you might learn a LOT by
> doing it.
>
> Tom
Received on Fri Apr 06 2001 - 15:52:03 NZST