maximum entropy writes:

>>From: Simon Burge <simonb@telstra.com.au>

    [troubles with Mona]


>Make sure the kernel and *all* of userland on mona (especially /bin
>and /sbin which are not on the shared /usr filesystem) are up to date.
>Reboot mona and all should be well.

>This isn't really a kernel problem, it's caused by out-of-date
>userland binaries but up-to-date shared libs.


The glass is half full, or the glass is half empty.  It's still the same glass.

The problem is that the accidentally-updated /usr makes syscalls which
are not implemented by the 1.2G kernel.  Which you call out-of-date
and which up-to-date is semantics. Simon didn't realize a `make build'
on one machine would also clobber the NFS-mounted /usr on the second
machine.

The simplest way to rescue Mona is to netboot a kernel that *does*
have the new xxx13 syscalls (from the good machine) on Mona. Then
mount Mona's local root as root.  The updated /usr will then work,
because the net-booted-mounted kernel has the 1.3 syscalls.  Then
proceed to do an upgrade on the affected machine. 

(I'm saying this only in case the same thing happens to someone else.)