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zidarsk8

Member

Registered: 2011-12-06

Posts: 97

renaming md0 raid array

Hi, I have a raid array that was made with

mdadm --create /dev/md0 ....

but after every reboot that gets renamed to md127

installing my system on such an array worked fine, but after the first reboot, the kernel doen't find the LVM on that raid array. I am not even sure if the renaming is the problem or not.

my questions is, should the wiki for Software raid and LVM use /dev/md0 for pvcreate or should that be the symlink that is suppose to always stay the same /dev/md/name

source for renaming -> https://bugzilla.redhat.com/show_bug.cgi?id=606481

wiki article -> https://wiki.archlinux.org/index.php/So … stallation

lilsirecho

Veteran

Registered: 2003-10-24

Posts: 5,000

Re: renaming md0 raid array

Perhaps you can try the following procedure............

mdadm --stop /dev/md127
mdadm --assemble /dev/md(x) /dev/sd(x) /dev/sd(y)   ......Use desired devices

This will allow you to address /dev/md(x) and examine it in a mount.

You may get a better performing setup if you use a different number for the md array, such as md2.

I think that the zero is not valid in the latest handling of arrays AFAICT.

I use this arrangement in my raid0 bootable partitioned grub2 devices.

Changing the number does not affect the content.

Let us know if it was helpful....

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zidarsk8

Member

Registered: 2011-12-06

Posts: 97

Re: renaming md0 raid array

on the wiki we have

# mdadm --create /dev/md0 --level=5 --raid-devices=3 /dev/sd[abc]3

# mdadm --create /dev/md1 --level=1 --raid-devices=3 /dev/sd[abc]2 # for boot

and so on

and all i know is that right now my system won't boot because it it can't find LVM devices on md0 (and i am assuming that's because it got renamed to md127)

"I think that the zero is not valid in the latest handling of arrays AFAICT."
every line in the Raid wiki starts with md0, so if that's the case, wiki should be changed.

PS: i really don't know much about all this, all i know is i'm having problems and trying to figure out what those might be.

jasonwryan

Anarchist

From: .nz

Registered: 2009-05-09

Posts: 30,424

Website

Re: renaming md0 raid array

md0 is fine for a name.

You'll need to post your: {syslinux,boot} config file, hooks from your mkinitcpio and your mdadm.conf to help narrow down what the issue might be...

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zidarsk8

Member

Registered: 2011-12-06

Posts: 97

Re: renaming md0 raid array

Problem: I install arch on a raid array, and after a few reboots, i get the error "no volume groups found"

here's my grub config file http://pastebin.com/RNVQju3K

stuff in my mkinintcopio.conf (just what i've changed)

MODULES="[b]dm_mod raid1 raid5[/b]"
HOOKS="base udev autodetect pata scsi sata [b]mdadm_udev lvm2[/b] filesystems usbinput fsck"

my mdadm.conf

ARRAY /dev/md/raid_boot metadata=1.2 UUID=93fa7b5a:f6927353:0ccfa543:9915b56e name=dog:raid_boot
ARRAY /dev/md/muc metadata=1.2 UUID=f3445f73:70530dc7:8b8d64ed:f6617cd6 name=dog:muc

and i've added this line in rc.conf

USELVM="yes"

Hope this is enough to narrow down the issue. Thanks

jasonwryan

Anarchist

From: .nz

Registered: 2009-05-09

Posts: 30,424

Website

Re: renaming md0 raid array

I don't use Grub, but this looks confusing to me:

set root='lvm/RaidMasterArray-lvroot'
...
set root='lvm/RaidBootArray-lvboot'

Also, the UUIDs in your mdadm.conf do not match those in your grub.cfg.

It is also odd that it boopts successfully a couple of times...

Perhaps someone familiar with how Grub2 works can offer more constructive suggestions.

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zidarsk8

Member

Registered: 2011-12-06

Posts: 97

Re: renaming md0 raid array

yeah, it's weird,

but the grub configuration is auto generated with this

grub-mkconfig -o /boot/grub/grub.cfg

so it should be okay. UUIDs might be different, since those might be IDs from the virtual devices created by the LVM and the mdadm.conf contains the UUID of the raid devices (LVM partition with their id's are on top of the raid device)

and yeah, I have succesfully rebooted 10 times now, and now i'm getting the same error. I also think this might be a hardware error, but on the other hand it's a brand new machine, and installing ubuntu on it worked normally. Just without the raid.