[SOLVED] How create RAID 1 on working Slackware 14.2?

infernalcucumber · 12-04-2019, 09:57 PM

Hi! I use Slackware 14.2 (with kernel 4.4.14-smp) on sda and I'm trying to create the RAID 1 with additional sdb. I'm using the VM VirtualBox.

First, I have cleaned the sdb:

Code:

dd if=/dev/zero of=/dev/sdb bs=8M count=1000

and copied the sda's partitions to sdb:

Code:

sfdisk -d /dev/sda | sfdisk /dev/sdb

Next, I've changed the type of partitions to "Linux raid autodetect":

Code:

Device     Boot     Start       End   Sectors Size Id Type
/dev/sda1            2048   8390655   8388608   4G 82 Linux swap
/dev/sda2  *      8390656 113248255 104857600  50G 83 Linux
/dev/sda3       113248256 209715199  96466944  46G  5 Extended
/dev/sda5       113250304 144707583  31457280  15G 83 Linux
/dev/sda6       144709632 176166911  31457280  15G 83 Linux
/dev/sda7       176168960 209715199  33546240  16G 83 Linux

and

Code:

Device     Boot     Start       End   Sectors Size Id Type
/dev/sdb1            2048   8390655   8388608   4G fd Linux raid autodetect
/dev/sdb2  *      8390656 113248255 104857600  50G fd Linux raid autodetect
/dev/sdb3       113248256 209715199  96466944  46G  5 Extended
/dev/sdb5       113250304 144707583  31457280  15G fd Linux raid autodetect
/dev/sdb6       144709632 176166911  31457280  15G fd Linux raid autodetect
/dev/sdb7       176168960 209715199  33546240  16G fd Linux raid autodetect

For each partition (md1,md2,md5,md6,md7), I did next:

Code:

mdadm --create /dev/md1 --level=1 --metadata=0.90 --raid-disk=2 missing /dev/sdb1

and made filesystems on created arrays:

Code:

mkswap /dev/md1
mkreiserfs -fq /dev/md2
mkreiserfs -fq /dev/md5
mkreiserfs -fq /dev/md6
mkreiserfs -fq /dev/md7

saved the raid configuration:

Code:

mdadm --examine --scan >> /etc/mdadm.conf

Next, /etc/fstab and /etc/mtab were edited by replacing sdaX->mdX and the initial ramdisk were prepared:

Code:

mkinitrd -c -k 4.4.14-smp -f reiserfs -r /dev/md2 -m reiserfs:dm-raid -u -o /boot/initrd_raid.gz

Configured the grub:

Code:

cp /etc/grub.d/40_custom /etc/grub.d/09_swraid1_setup
#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
menuentry 'Slackware-14.2 GNU/Linux' --class slackware-14.2 --class gnu-linux --class os {
    insmod raid
    insmod mdraid
    insmod mdraid09
    insmod mdraid1x
    insmod gzio
    insmod part_msdos
    insmod reiserfs
    set root='md2,msdos2'
    echo    'Loading Linux 4.4.14-smp ...'
    linux   /boot/vmlinuz-huge-smp-4.4.14-smp root=/dev/md2 ro
    echo    'Loading inital ramdisk ...'
    initrd  /boot/initrd_raid.gz
}

I have edited the /etc/default/grub by uncomment:

Code:

GRUB_TERMINAL=console
GRUB_DISABLE_LINUX_UUID=true

Finally:

Code:

grub-mkconfig -o /boot/grub/grub.cfg
grub-install /dev/sda/
grub-install /dev/sdb/

And data were copied from sda to sdb (cp -dpRx / /mnt/md2 and etc.).

After rebooting I got error that raid.mod and mdraid.mod not found and device 'md2,msdos2' not found.

The question is: which modules should I add to initrd and how should I config the grub?

Thanks.

Ser Olmy · 12-08-2019, 07:46 PM

At the time I post this, your post has been viewed 88 times but there have been no replies.

I believe this is because your post is quite confusing: it seems you haven't read the RAID How-Tos, and it also seems you've left out some information.

For instance:

Quote:

Originally Posted by infernalcucumber

First, I have cleaned the sdb:

Code:

dd if=/dev/zero of=/dev/sdb bs=8M count=1000

Now, why would you do that? Surely, a new virtual disk is by definition empty?

Continuing on:

Quote:

Originally Posted by infernalcucumber

and copied the sda's partitions to sdb:

Code:

sfdisk -d /dev/sda | sfdisk /dev/sdb

You mean you copied the partition table. It seems this procedure would also transfer the label ID of the source disk onto the destination disk, which is a bad idea if you want to have both disks connected to the same system.

Quote:

Originally Posted by infernalcucumber

Next, I've changed the type of partitions to "Linux raid autodetect":

Quote:

Originally Posted by infernalcucumber

For each partition (md1,md2,md5,md6,md7), I did next:

Code:

mdadm --create /dev/md1 --level=1 --metadata=0.90 --raid-disk=2 missing /dev/sdb1

The fact that you're creating degraded mirror sets indicates that you want to copy existing data from the various partitions on /dev/sda and then add these partitions to the RAID sets afterwards, but why are you using metadata v0.90 for all the md devices?

Quote:

Originally Posted by infernalcucumber

saved the raid configuration:

Code:

mdadm --examine --scan >> /etc/mdadm.conf

Next, /etc/fstab and /etc/mtab were edited by replacing sdaX->mdX

I'd just like to point out that this will only work if /etc/mdadm.conf is present in the initrd image.

The initrd boot script will indeed activate the RAID sets, but unless /etc/mdadm.conf is present, the RAID devices will be dynamically named using a particular numbering scheme, starting from /dev/md127 and counting downwards. This will obviously not match /etc/fstab on your root partition, so when the time comes for the startup script to remount root as read/write, it won't find root at all and you'll be unceremoniously dumped at a recovery console.

Consider using UUIDs or labels instead.

Also, you left out the part where you (presumably) transferred files from /dev/sdaX to the various md devices.

Quote:

Originally Posted by infernalcucumber

and the initial ramdisk were prepared:

Code:

mkinitrd -c -k 4.4.14-smp -f reiserfs -r /dev/md2 -m reiserfs:dm-raid -u -o /boot/initrd_raid.gz

There are two issues with that command:

1. From man mkinitrd:

Code:

-R     This option adds RAID support to the initrd, if a static mdadm binary is available on the system.

2. dm-raid.ko has nothing to do with mdadm support. "dm" stands for "device mapper", aka LVM. The module you're looking for is called raid1.

I don't know how grub handles mdadm RAID sets, but it seems you've added more modules to grub.cfg than needed.