Problems using multipath _ md _ lvm with IBM Series I and DS8000

[George Magklaras]

Hmm,

I have seen something on a recent RHN release for a new kernel fix. It 
came in yesterday and for what you describe, it looks as if your 
device-mapper-multipath module code is causing the problem. Do you have 
the problem with the latest new kernel? (see below)

GM

-- 
--
George Magklaras

Senior Computer Systems Engineer/UNIX Systems Administrator
EMBnet Technical Management Board
The Biotechnology Centre of Oslo,
University of Oslo
http://folk.uio.no/georgios



Bug Fix Advisory - RHBA-2008:0128-3
------------------------------------------------------------------------------
Summary:
device-mapper-multipath bug fix update

Updated device-mapper-multipath packages that fix a bug are now available.

Description:
The device-mapper-multipath packages provide tools to manage multipath
devices by giving the device-mapper multipath kernel module instructions on
what to do, as well as by managing the creation and removal of partitions
for device-mapper devices.

These updated device-mapper-multipath packages fix a bug that occurs when
running multipath on a device containing the root filesystem. On such
systems, multiple path faults and recovery events could result in the
multipathed host becoming unresponsive.

In order to bring a failed path back online, some multipath devices require
a priority callout program. These programs are located on a ramfs; however,
they were not statically compiled, and needed libraries that were located
on the root filesystem. To fix this, all priority callouts are now
statically compiled.

Users are advised to upgrade to these updated device-mapper-multipath
packages, which resolve this issue.

Hartung, Christopher wrote:
> Hi @all,
> 
> We've problem installing redhat 5.1 on IBM Power System i 570 native.
> Our configuration will look like this:
> 
> DS8000_1	=> LUNA	=>	mpath (device-mapper)	=>	PrepBoot
> (8 MB), /boot (100 MB), / (rest)
> DS8000_2	=> LUNB	=>	mpath (device-mapper)	=>	PrepBoot
> (8 MB), /boot (100 MB), / (rest)
> 
> Mirroring:
> 		=> /boot	=> MD0
> 		=> /		=> MD1		=> lvm
> 
> so we've this layers: mpath - md - lvm
> 
> the installation of redhat works fine. But after starting the
> initprocess of our new system and initialization of the multipath
> devices the system can't found any md devices and in effect of this the
> system can't find the lvm configuration and gets a kernel panic because
> the root filesystem isn't found. 
> 
> We found many entrys in mailinglists to configure an new initramdisk but
> not really explained in detail. The questions are, would a new init
> solve our problem (if so, what must we do?) and would this configuration
> above work in this constellation?
> 
> Thanks for your answer in advance
> 
> So long,
> 
> christopher
>