How do I reference logical drives when booting from RedHat recovery CD

I'm working on a recovery scenario where I boot off a RedHat rescue CD and mount and restore data from a mirrored set of hard drives.

Currently my DL380-G4 has 2 logical drives - both Raid 1. ( so 4 drives total)

I'm asuming Raid #1 will fail at some point and I will need to recover from Raid #2.

When I boot off CD to linux rescue and attempt to mount /dev/cciss/c0d0p1 /recovery (Raid #2)It mounts Raid #1.

I guess I don't know enough about how to reference the logical drives especially when booting from Red Hat's rescue CD.

How do I refer to Raid #2 and how do I mount it? Can someone give me some pointers? Thanks.

7 REPLIES 7

To list the devices and partitions, use fdisk -l. I think that the second RAID will be /dev/cciss/c0d1p1.

You can post the results of fdisk -l.

Do you use the second raid as backup of the first? I mean, do you want to recover the data on the first array from the second right?

Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?

When I boot from the Linux rescue CD,
sfdisk -l gives me:

/dev/cciss/c0d0p1 0+ 12 13- ... Linux
/dev/cciss/c0d0p2 13 4426 352... Linux LVM
/dev/cciss/c0d0p3 0 - 0 0 0 Empty
/dev/cciss/c0d0p4 0 - 0 0 0 Empty

attempting to mount /dev/cciss/c0d0p3 gives me no such device or address.

Thanks for your help!

-tom

Please post also the output of fdisk -l and cat /proc/mounts when the system is not in rescue mode. It seems that you are seeing only one array with two partitions.

Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?

Here is the output after booting normally.

-tom

fdisk -l
Disk /dev/cciss/c0d0 36.4GB
/dev/cciss/c0d0p1 * 1 13 10491 83 Linux
/dev/cciss/c0d0p2 * 14 35455455 8e Linux LVM

Disk /dev/cciss/c0d1:36.4 GB
/dev/cciss/c0d1p1 1 37 150944 83 Linux

sudo cat /proc/mounts

rootfs / rootfs rw 0 0
/proc /proc proc rw, nodiratime 0 0
non /dev tmpfs rw 0 0
/dev/root / ext3 rw 0 0
none /dev /tmpfs rw 0 0
none /selinux selinuxfs rw 0 0
/proc /proc proc rw,nodiratime 0 0
/proc /bus/usb /proc/bus/usb usbfs rw 0 0
/sys /sys sysfs rw 0 0
non /dev/pts devpts rw 0 0
/dev/cciss/c0d0p1 /boot ext3 rw 0 0
none /dev/shm tmpfs rw 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw 0 0
sunrpc /var/lib/nfs/rpc_pipefs rpc_pipefs rw 0 0
/dev/cciss/c0d0p1 /recovery ext3 rw 0 0

Thanks.

Some problem exists when you boot form the CD, as you can see, normally you see:

Disk /dev/cciss/c0d0 36.4GB
Disk /dev/cciss/c0d1:36.4 GB

But in rescue, you don't see c0d1. You should try forcing scsi rescan with this script:

www.garloff.de/kurt/linux/rescan-scsi-bus.sh

Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?

Also, you are using LVM in the first array, to mount the device you should use the /dev/vgname/lvname, instead of the partition name!!

Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?

Sorry, in rescue mode, the LVM devices are under the /dev/mapper directory (?):

See this info:

http://www.centos.org/docs/4/html/rhel-sag-en-4/s1-rescuemode-boot.html

Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?