Bug 455660

Description of problem:
Installing OS with 2 controllers, with option "linux mpath", would install the 
OS on the mpath device, so the /root device is configured on multipath devices.
But the same, if tried with installing the OS with only one controller and then 
adding the second controller later after installation, would not let the /root 
be configured under multipath device.

Version-Release number of selected component (if applicable):
RHEL 5.1 (32 bit and 64 bit)

How reproducible:
With Dual Controllers present :  
- Install RHEL 5.1 with option “linux mpath” 
- Partition manager shows you the devices as /dev/mpath0  
- Proceed with installation and complete it. Installation goes fine. 
- Once rebooted successfully, run “multipath –ll”; we can see that the /root 
device (which lies on mpath0) is configured under multipath 
 
[root@localhost ~]# multipath -ll 
mpath1 (22298000155714d81) dm-5 Intel,Multi-Flex 
[size=5.0G][features=1 queue_if_no_path][hwhandler=1 intel] 
\_ round-robin 0 [prio=50][active] 
 \_ 0:0:0:1 sdb 8:16  [active][ready] 
\_ round-robin 0 [prio=1][enabled] 
 \_ 0:0:3:1 sdd 8:48  [active][ready] 
mpath0 (2220400015593d28b) dm-0 Intel,Multi-Flex 
[size=20G][features=1 queue_if_no_path][hwhandler=1 intel] 
\_ round-robin 0 [prio=50][active] 
 \_ 0:0:0:0 sda 8:0   [active][ready] 
\_ round-robin 0 [prio=1][enabled] 
 \_ 0:0:3:0 sdc 8:32  [active][ready] 
- My OS is on dm-0, which is 20G 
- The reason why /root could be configured under multipath in the above step is 
because the option at installation “linux mpath” add multipath modules in the 
boot image, so before the OS could be loaded, multipath modules are already 
loaded. 
- Hence the /root can be loaded on the  
 
 
With Single controller: 
- Install RHEL 5.1 with option “linux mpath” 
- Partition manager shows you the devices as /dev/sda, as there is one 
device/path per LUN. 
- Proceed with installation and complete it. Installation goes fine. 
- Once rebooted, add the second controller in and reboot (just make sure the 
devices are rescanned properly) 
- Once rebooted successfully, run “multipath –ll”; we can see that the /root 
device (which lies on mpath0) is NOT configured under multipath. 
[root@localhost ~]# multipath -ll 
mpath0 (22298000155714d81) dm-0 Intel,Multi-Flex 
[size=5.0G][features=1 queue_if_no_path][hwhandler=1 intel] 
\_ round-robin 0 [prio=50][active] 
 \_ 0:0:0:1 sdb 8:16  [active][ready] 
\_ round-robin 0 [prio=1][enabled] 
 \_ 0:0:1:1 sdd 8:48  [active][ready] 
 
- I can see only one LUN configured under multipath, which does not have any OS 
component (/root, /boot, swap) 
- So the problem here is as the multipath modules are not part of the boot 
image and are not set in the right sequence to load, /root loads first and 
multipath loads later. 
- Now that the /root device is already loaded it can’t configured under 
multipath. 
- The solution probably is to make a new initrd image with dm-multipath module. 
- We tried that but still the /root device won’t get configured under 
multipath. 


Steps to Reproduce:
1. Mentioned above.
  
Actual results:
/root can not be configured on multipath devices with initially installed the 
OS with single controller.

Expected results:
Os should allow /root to be configured under multipath

Additional info: