+++ This bug was initially created as a clone of Bug #482753 +++

Arnaldo hit the warning that Shak and Jcm have seen earlier and investigated the issue a bit.

That seems to be the origin of this issue:

# rpm -q --changelog mkinitrd
* Wed Dec 17 2008 Peter Jones <pjones> - 5.1.19.6-44
 - Include dm-raid45 and related modules if dmraid is in use.
   Resolves: rhbz#476866

Symptoms:

# mkinitrd /boot/initrd-2.6.24-100.el5rt.tsc1.img 2.6.24-100.el5rt.tsc1
No module dm-mem-cache found for kernel 2.6.24-100.el5rt.tsc1, aborting.

or

# /sbin/new-kernel-pkg --package kernel-rt --banner "Red Hat Enterprise Linux (realtime)" --mkinitrd --depmod --install 2.6.24-100.el5rt.tsc1
WARNING: No module dm-mem-cache found for kernel 2.6.24-100.el5rt.tsc1, continuing anyway
WARNING: No module dm-region_hash found for kernel 2.6.24-100.el5rt.tsc1, continuing anyway
WARNING: No module dm-message found for kernel 2.6.24-100.el5rt.tsc1, continuing anyway
WARNING: No module dm-raid45 found for kernel 2.6.24-100.el5rt.tsc1, continuing anyway

--- Additional comment from jneedle on 2009-02-03 11:36:59 EDT ---

Good news and bad news.  mkinitrd-5.1.19.6-44 only shipped in 5.3, and since the 1.1.1 candidate was shipped for 1.1, we support 5.2.  This will have to be revisited, though, when the next release goes out that targets 5.3.

--- Additional comment from lgoncalv on 2009-03-03 15:40:36 EDT ---

Created an attachment (id=333925)
Patch for the mkinitrd/dmraid issue

One possible solution.

This patch creates a functions called try_findmodule(), used only to locate dmraid modules, that will silently ignore these modules if they are not present in the kernel being installed.

By the number of reports we received about the mkinitrd WARNINGS during MRG RT kernel installation, I believe support folks will like this solution best as it may avoid bogus support tickets.

before:
   # mkinitrd /boot/initrd-2.6.24.7-107.el5rt.img 2.6.24.7-107.el5rt
   No module dm-mem-cache found for kernel 2.6.24.7-107.el5rt, aborting.

After:

   # mkinitrd /boot/initrd-2.6.24.7-107.el5rt.img 2.6.24.7-107.el5rt
   #

--- Additional comment from lgoncalv on 2009-03-03 15:44:35 EDT ---

Created an attachment (id=333927)
Another patch for the mkinitrd/dmraid issue

Another possible solution [ just for the sake of completeness as the other patch is better ].

This patch creates a functions called try_findmodule(), used only to locate
dmraid modules, that will ignore these modules if they are not present
in the kernel being installed, but will issue the scary warning from mkinitrd.

By the number of reports we received about the mkinitrd WARNINGS during MRG RT
kernel installation, I believe support folks will preffer the other solution as it may avoid bogus support tickets.

before:
   # mkinitrd /boot/initrd-2.6.24.7-107.el5rt.img 2.6.24.7-107.el5rt
   No module dm-mem-cache found for kernel 2.6.24.7-107.el5rt, aborting.

After:

   # mkinitrd /boot/initrd-2.6.24.7-107.el5rt.img 2.6.24.7-107.el5rt
   WARNING: No module dm-mem-cache found for kernel 2.6.24.7-107.el5rt, continuing anyway
   WARNING: No module dm-region_hash found for kernel 2.6.24.7-107.el5rt, continuing anyway
   WARNING: No module dm-message found for kernel 2.6.24.7-107.el5rt, continuing anyway
   WARNING: No module dm-raid45 found for kernel 2.6.24.7-107.el5rt, continuing anyway