Software RAID using mdadm

onthefritz · 12-08-2009, 02:13 PM

Ok, I need some help setting up software RAID. I am running RHEL 4.6 AS. Here is my configuration:

48 disks
one RAID1 with 2 disks and using LVM (for / and SWAP)
three RAID10 with 6 disks +1 spare and LVM across the 3 arrays(for /home)
two RAID10 with with 6 disks +1 spare and LVM across the 2 arrays (for /opt)

I setup the RAID1, and had the VLM that / is on grow to incorporate /dev/md0. Then i used pvmove to more the data from /dev/sdaa to /dev/md0. (from the install drive, to the RAID1.) I have the mdadm.conf file configured and I thought I setup the initrd image correctly. But when I boot, I get a kernel panic and it dies.

If you need more info, please just ask.

OTF

eco · 12-08-2009, 04:52 PM

Hi,

With a setup like this one, I'm wondering why you're not using a hardware RAID but that's besides the point I guess.

I'm not quite sure what you are trying to do but you can have RAID1 for root by seting up a degraded RAID and then syncing the disks. Don't forget to put the boot sector on both disks so that if the 'primary' one fails, you can still boot on the other.

There is loads of doc out there on getting a degraded RAID setup and back in sync.

As for the boot sector thing, here is an example on how I did it:

Install boot record on hda and hdc

Code:

livecd linux # grub --no-floppy --device-map=/boot/grub/device.map

grub> device (hd0) /dev/hda
grub> root (hd0,0)
grub> setup (hd0)

grub> device (hd0) /dev/hdc
grub> root (hd0,0)
grub> setup (hd0)

grub> quit

DrLove73 · 12-09-2009, 03:38 AM

I was unable to boot from RAID-ed /boot partition, what ever I did. That is on CentOS 5.3 and 5.4. I disassembled boot RAID, set grub boot sector on both disks (RAID1), and I am now booting from only one disk, but other one is manualy replicated whenever I update kernel.