[dm-devel] Configuring multipath for root device

[malahal at us.ibm.com]

Pradipmaya Maharana [pradipmaya at gmail.com] wrote:
> Ok, so this is what the scene is :
> 
> linux-g78h:~ # ls -al /dev/disk/by-id/
> total 0
> drwxr-xr-x 2 root root 220 Jan  7 12:44 .
> drwxr-xr-x 5 root root 100 Jan  7 12:44 ..
> lrwxrwxrwx 1 root root   9 Jan  7 12:44 edd-int13_dev80 -> ../../sda
> lrwxrwxrwx 1 root root  10 Jan  7 12:44 edd-int13_dev80-part1 -> ../../sda1
> lrwxrwxrwx 1 root root  10 Jan  7 12:44 edd-int13_dev80-part2 -> ../../sda2
> lrwxrwxrwx 1 root root  10 Jan  7 12:44 edd-int13_dev80-part3 -> ../../sda3
> lrwxrwxrwx 1 root root   9 Jan  7 12:44 scsi-2221b000155f5d2d4 -> ../../sdb
> lrwxrwxrwx 1 root root  10 Jan  7 12:44 scsi-2221b000155f5d2d4-part1
> -> ../../sda1
> lrwxrwxrwx 1 root root  10 Jan  7 12:44 scsi-2221b000155f5d2d4-part2
> -> ../../sda2
> lrwxrwxrwx 1 root root  10 Jan  7 12:44 scsi-2221b000155f5d2d4-part3
> -> ../../sda3
> lrwxrwxrwx 1 root root   9 Jan  7 12:44 usb-ASUS_CB-5216A_DEF10A4090DF
> -> ../../sr0
> linux-g78h:~ #
> linux-g78h:~ # uname -a
> Linux linux-g78h 2.6.16.46-0.12-smp #1 SMP Thu May 17 14:00:09 UTC
> 2007 i686 i686 i386 GNU/Linux
> linux-g78h:~ #
> linux-g78h:~ # cat /etc/grub.conf
> setup --stage2=/boot/grub/stage2 (hd0,0) (hd0,0)
> quit
> linux-g78h:~ #
> linux-g78h:~ # cat /boot/grub/menu.lst
> # Modified by YaST2. Last modification on Mon Jan  7 19:40:30 UTC 2008
> default 0
> timeout 8
> ##YaST - generic_mbr
> gfxmenu (hd0,0)/message
> ##YaST - activate
> 
> ###Don't change this comment - YaST2 identifier: Original name: linux###
> title SUSE Linux Enterprise Server 10 SP1
>     root (hd0,0)
>     kernel /vmlinuz-2.6.16.46-0.12-smp root=/dev/sda2 vga=0x31a
> resume=/dev/sda3 showopts
>     initrd /initrd-2.6.16.46-0.12-smp
> 
> ###Don't change this comment - YaST2 identifier: Original name: failsafe###
> title Failsafe -- SUSE Linux Enterprise Server 10 SP1
>     root (hd0,0)
>     kernel /vmlinuz-2.6.16.46-0.12-smp root=/dev/sda2 vga=normal
> showopts ide=nodma apm=off acpi=off noresume nosmp noapic maxcpus=0
> edd=off 3
>     initrd /initrd-2.6.16.46-0.12-smp
> 
> ###Don't change this comment - YaST2 identifier: Original name: linux###
> title SUSE Linux Enterprise Server 10 SP1 ORG
>     root (hd0,0)
>     kernel /vmlinuz-2.6.16.46-0.12-smp root=/dev/sda2 vga=0x31a
> resume=/dev/sda3 showopts
>     initrd /initrd-2.6.16.46-0.org.12-smp
> 
> 
> So, I modified the fstab and menu.lst to replace all /dev/sdaX with
> /dev/scsi-2221b000155f5d2d4-partX. It won't boot.

/dev/scsi-2221b000155f5d2d4-partX is bogus! Your root device /dev/sda2
actually is edd-int13_dev80-part2, specifically it is
/dev/disk/by-id/edd-int13_dev80-part2.  You should replace /dev/sdaX
with /dev/disk/by-id/edd-int13_dev80-partX

Also, make sure that what ever you replace with is a valid name. For
example, /dev/scsi-2221b000155f5d2d4-partX will NOT exist on your
system where as /dev/disk/by-id/edd-int13_dev80-part2 should exist.