Arch Linux

Pacopag

Member

Registered: 2011-05-29

Posts: 287

[SOLVED] Arch is on /dev/sdb but I want to remove /dev/sda

Hi.  I've got 3 drives in my tower:  sda, sdb and sdc.  Arch is installed on sdb, but I want to physically remove the drive at sda. When I unplug the drive I get the syslinux menu at boot, but it ends up saying something like
"Root device mounted successfully, but /sbin/init does not exist....You're on your own", and it doesn't boot. If I plug the drive back in, it boots fine.

I'm not sure what's happening here, but I think it has something to do with the fact that I'm unplugging sda, then sdb/sdc get re-mapped to sda/sdb, or something like that.  Right now my syslinux.cfg looks like this (note the  APPEND root=/dev/sdb1 rw)

DEFAULT arch
PROMPT 0        # Set to 1 if you always want to display the boot: prompt 
TIMEOUT 50
# You can create syslinux keymaps with the keytab-lilo tool
#KBDMAP de.ktl

# Menu Configuration
# Either menu.c32 or vesamenu32.c32 must be copied to /boot/syslinux 
UI menu.c32
#UI vesamenu.c32

# Refer to http://syslinux.zytor.com/wiki/index.php/Doc/menu
MENU TITLE Arch Linux
#MENU BACKGROUND splash.png
MENU COLOR border       30;44   #40ffffff #a0000000 std
MENU COLOR title        1;36;44 #9033ccff #a0000000 std
MENU COLOR sel          7;37;40 #e0ffffff #20ffffff all
MENU COLOR unsel        37;44   #50ffffff #a0000000 std
MENU COLOR help         37;40   #c0ffffff #a0000000 std
MENU COLOR timeout_msg  37;40   #80ffffff #00000000 std
MENU COLOR timeout      1;37;40 #c0ffffff #00000000 std
MENU COLOR msg07        37;40   #90ffffff #a0000000 std
MENU COLOR tabmsg       31;40   #30ffffff #00000000 std

# boot sections follow
#
# TIP: If you want a 1024x768 framebuffer, add "vga=773" to your kernel line.
#
#-*

LABEL arch
    MENU LABEL Arch Linux
    LINUX ../vmlinuz-linux
    APPEND root=/dev/sdb1 rw
    INITRD ../initramfs-linux.img

LABEL archfallback
    MENU LABEL Arch Linux Fallback
    LINUX ../vmlinuz-linux
    APPEND root=/dev/sdb1 rw
    INITRD ../initramfs-linux-fallback.img

#LABEL windows
#        MENU LABEL Windows
#        COM32 chain.c32
#        APPEND hd0 1

LABEL hdt
        MENU LABEL HDT (Hardware Detection Tool)
        COM32 hdt.c32

LABEL reboot
        MENU LABEL Reboot
        COM32 reboot.c32

LABEL poweroff
        MENU LABEL Poweroff
        COM32 poweroff.c32

And fstab looks like this

# /dev/sdb1
UUID=54ece8c2-8998-4203-b2f8-66cb682e4bf0	/         	ext4      	rw,relatime,data=ordered	0 1

# /dev/sdb2
#UUID=81fa4eea-4503-4fc5-8418-1fab3e753413	none      	swap      	defaults  	0 0

I'm tempted to change sdb to sda in syslinux.cfg, and change the UUID=... to /dev/sda1 in fstab, but I don't want to screw with anything boot related since it's a really bad time for me to end up with a system that won't boot.

Am I on the right track here?

If I go ahead and make those changes, unplug the drive and end up with a system that won't boot, can I just go in there with a live-cd, change them back and expect it to boot as before...is that safe?

Last edited by Pacopag (2014-09-05 15:26:39)

tomk

Forum Fellow

From: Ireland

Registered: 2004-07-21

Posts: 9,839

Re: [SOLVED] Arch is on /dev/sdb but I want to remove /dev/sda

How did you end up with /dev/sd* in one config and UUID in the other anyway? Just use the UUID everywhere.

Pacopag

Member

Registered: 2011-05-29

Posts: 287

Re: [SOLVED] Arch is on /dev/sdb but I want to remove /dev/sda

...by not reading the docs carefully enough...

So you're saying to change my APPEND root=UUID=54ece8c2-8998-4203-b2f8-66cb682e4bf0

in syslinux.cfg

And I should be able to boot with my other drives unplugged?

Last edited by Pacopag (2014-09-05 15:16:27)

jwm-art

Member

Registered: 2011-02-01

Posts: 87

Re: [SOLVED] Arch is on /dev/sdb but I want to remove /dev/sda

Yes, change them all to use UUIDs.

You could also try editing the boot options before booting the system, and change sdb to sda, just to get it to boot, before changing the config to use UUIDs.

Pacopag

Member

Registered: 2011-05-29

Posts: 287

Re: [SOLVED] Arch is on /dev/sdb but I want to remove /dev/sda

Yep.  Changing to UUID in syslinux.cfg did the trick.  Thanks a whole bunch.