Hi,
grub-probe is unable to handle multipath devices:

node1:~# dpkg --configure -a
Setting up grub-pc (1.97+20091115-1) ...
Generating core.img
grub-probe: error: no mapping exists for `mpath0-part1'
Auto-detection of a filesystem module failed.
Please specify the module with the option `--modules' explicitly.
dpkg: error processing grub-pc (--configure):
 subprocess installed post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of grub:
 grub depends on grub-pc; however:
  Package grub-pc is not configured yet.
dpkg: error processing grub (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 grub-pc
 grub

This breaks upgrades from Lenny to sid. The multipath map is:

# multipath -l
mpath0 (SQEMU   QEMU HARDDISK  ) dm-0 QEMU,QEMU HARDDISK
size=10G features='0' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=-1 status=active
  `- 0:0:0:0 sda 8:0 active undef running

# dmsetup info /dev/mapper/mpath0
Name:              mpath0
State:             ACTIVE
Read Ahead:        256
Tables present:    LIVE
Open count:        2
Event number:      1
Major, minor:      254, 0
Number of targets: 1
UUID: mpath-SQEMU   QEMU HARDDISK

Reinstalling grub-legacy works around the issue.
Cheers,
 -- Guido

Am Samstag, den 21.11.2009, 18:30 +0100 schrieb Guido Günther:

Looks like you forgot about 483971 and 442382.
and maybe even others. Haven't looked this multipath issue now all up.
But i remembered it was you who has interest in multipath support inside
debian-installer and so grub2 too.
I'm a bit unsure if I should just merge this with 483971 or reassign at
GRUB Legacy, where the dummy grub package still is, and add a debconf
note that gets shown when multipath is detected and tells people to keep
Legacy for now.

But it still looks like that you're the only one for whom multipath is
important. (Well and Frans who considers this as a blocker, but it
didn't block the switch to grub2 as default for d-i alpha1)

Hi Felix,
Thanks for the quick response.
Nope, I didn't. This one is different as it breaks upgrades from
existing and supported installations.
That would at least be a workaround.
Don't think so. Multipath is run in "enterprise" environments where
people are much more conservative regarding upgrades. I'm starting to
get reports from etch->lenny upgrades so don't expect many others to
notice within the next year.
Cheers,
 -- Guido

forcemerge 483971 557359
thanks

Am Samstag, den 21.11.2009, 20:53 +0100 schrieb Guido Günther:

It is not different. The older ones were reassigned to grub-common and
you filed this against grub-common (actually even grub-probe).
If it's more important then wishlist then the severity of that bug needs
to be changed and not a new one filed which exactly says the same: to
implement multipath support inside grub-probe.

Seems like I have to take it literarily that you get the reports.
The debian-testing mailing list were all upgrade-reports end doestn't
say anything about multipath back to 2008/12.