[PVE-User] PVE + software raid - boot process

[Pongracz Istvan]

2008. 11. 4, kedd keltezéssel 15.13-kor Pongracz Istvan ezt írta:
> Hi,
> 
> I successfully migrated the PVE installation to a software raid1
> configuration.
> 
> The base system (/, /boot, swap) are on a hard drive and the data is on
> different raid1 disks.
> 
> So, my problem is, when I boot and I gave for the root /dev/md3, it
> cannot boot from the root raid1 array.
> If I give /dev/sda3 as root partition, it can boot, can use all raid
> devices, except md3.
> 
> So, I continue the work to solve this issue, but is there any hint where
> to find the Holy Grail?
> 
> As I looked into the initrd, it has no mdadm.
> My next probe to regenerate the initrd with mdadm.
> 
> Cheers,
> István
> 

Hi,

FYI: Solved with minimal modification.
It seems fully working.

Steps:
* Install a fresh PVE.
* Boot it.
* Install mdadm package.
* Reboot with systemrescuecd 1.x
* Create your preferred layout in the second drive, but force to use
only one device instead of at least two (--force --raid-devices 1)
* Mount your directory layout under /mnt/raid
* Mount "pve" layout under /mnt/pve
* rsync -a /mnt/pve/ /mnt/raid/
* umount the old (pve) layout
* copy the partition table from the second drive to the pve drive using
sfdisk -d /dev/sdb | sfdisk /dev/sda
* grow your raid devices from 1 device to 2
* add devices from sda to your raid arrays
* check /proc/mdstat 
* modify your fstab under /mnt/raid to fit the new config
* "dirty" hack needed to modify initrd to contain mdadm and a small
modification of init script to catch all raid devices, 
* modify your grub.conf: root=/dev/mdX and initrd must be the "new"
* more or less that's all

Notes:
* This is not a step-by-step for dummies, but a guide to those, who has
initial knowledge and want to learn more.
* AFAIK this is not really supported by PVE team :) (fix it)
* AFAIK this is not really recommended by PVE team :) (fix it)

Hints: 
* remove the pcspkr.ko driver to avoid beeps :)
* use a kvm machine with two drives (4-8GB each is enough to test it) to
test the process ;) 512MB ram is also enough.

Links: 
Systemrescuecd - http://www.sysresccd.org/Download.en.php
PVE - already well known

Regards,
István

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