CentOS - Jun 2010 - SUN Storage 7310 with RHEL 5.5 / Centos 5.5 and multipathed root, again.

Dear all,

After some trouble finding the right multipath.conf, I'm running Centos 
5.5 against the SUN 7310 more or less successfully now. Unfortunately one 
issue remains:

the SUN 7310 has two storage heads, H1 and H2, which are in a 
active/passive configuration. If I define a LUN on H1, everything works 
great. I edit multipath.conf, re-create the initrd and I find 8 paths with 
active/ready and active/ghost:

mpath0 (3600...0001) dm-0 SUN,Sun Storage 7310
[size=50G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=200][active]
 \_ 0:0:0:0 sda 8:0   [active][ready]
 \_ 0:0:1:0 sdd 8:48  [active][ready]
 \_ 1:0:0:0 sdg 8:96  [active][ready]
 \_ 1:0:1:0 sdj 8:144 [active][ready]
\_ round-robin 0 [prio=4][enabled]
 \_ 1:0:2:0 sdm 8:192 [active][ghost]
 \_ 0:0:2:0 sdn 8:208 [active][ghost]
 \_ 1:0:3:0 sds 65:32 [active][ghost]
 \_ 0:0:3:0 sdt 65:48 [active][ghost]

Thing is: as soon as I set up a machine with the LUN(s) on the second 
head, all works well until I want to boot with the freshly created 
initrd/multipath.conf. System hangs with Kernel Panic, "Creating multipath 
devices... no devices found" and "mount: could not find filesystem 
'/dev/root'".
Workaround: when I remove the paths to the passive ("ghost paths")
Storage
head in the SAN Fabric, the system boots fine and I can re-enable the 
paths when the kernel is up. The paths become [active][ghost] as wished 
after some time when they show up in the FC Zoning.

This smells like broken mkinitrd to me.

System is very up-to-date, Centos 5.5 Version below:

[root at dev-db3 ~]# yum list device-mapper-multipath
Installed Packages
device-mapper-multipath.x86_64    0.4.7-34.el5_5.1        installed
[root at dev-db3 ~]# uname -r
2.6.18-194.3.1.el5

Any suggestions?

best regards from Berlin,

Jens Neu
Health Services Network Administration
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