misc/55933: no dumpon/savecore with swap controlled by vinum

[Thorsten Kuehnemann]

>Number:         55933
>Category:       misc
>Synopsis:       no dumpon/savecore with swap controlled by vinum
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Aug 24 13:00:09 PDT 2003
>Closed-Date:
>Last-Modified:
>Originator:     Thorsten Kuehnemann
>Release:        FreeBSD 5.1-RELEASE-p2 i386
>Organization:
private
>Environment:
System: FreeBSD ef80.jnx.de 5.1-RELEASE-p2 FreeBSD 5.1-RELEASE-p2 #0: Wed Aug 20 13:41:44 CEST 2003 tk at ef80.jnx.de:/home/usr/obj/home/usr/src/sys/GENERIC-DEBUG i386

	GENERIC with
	"makeoptions     DEBUG=-g"
	enabled.

>Description:
	With two disks you can mirror all filesystems and swap with vinum
	to get uninterrupted service if one disk fails.

	If you use mirrored swap you run into two problems with
	kernel panics:

	1. The dumpon command does not accept vinum volumes. The
	   command "swapon /dev/vinum/swap" returns with the error message
		dumpon: ioctl(DIOCSKERNELDUMP): Inappropriate ioctl for device

	This is ok, because the
	dump is written late and saved early in boot sequence
	so it might suffice to calculate an overlay partition b
	on one disk (described in Chapter 13.9.2 in the Handbook for
	a root volume) to save the dump, giving /dev/da0s1b to the
	dumpon command. this works great but...

	2. the script "/etc/rc.d/savecore" refuses to save a dump
	   with the error message:
	     savecore: first and last dump headers disagree on /dev/vinum/swap
	     savecore: unsaved dumps found but not saved


	As a result you cannot save dumps on swap devices controlled
	by vinum.

>How-To-Repeat:
	
>Fix:
	Perhaps it is possible to change /etc/rc.d/savecore to explicit
	call savecore with the configured name of $dumpdev.

	A second fix might be to add the overlay device in /etc/fstab
	with a FStype of 'dump' (according to the manual page of savecore).
	You will get an error message for /dev/vinum/swap but the
	extra entry marked as 'dump' will work.
>Release-Note:
>Audit-Trail:
>Unformatted: