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I am using Gentoo Linux and for a while now, the root file system is mounted read-only on booting. For obvious reasons, this is quite annoying as most services do not start up correctly (I do not use a separate file system for /var). After the system is up, I have to log in, remount the root file system read-write, fix /etc/mtab, mount all other file systems in from /etc/fstab and then start up all the missing daemons. I know that there are ways to make a system run properly with a read-only file system, but I would rather restore the old behaviour of a writable root file system.

The strange thing is that after running mount / -o remount,rw, the file system is mounted in writable mode without any errors. I suspected some problem with fsck, but now I have disabled automatic file system checks on the partition (tune2fs -c0 -i0).

When I run dmesg, only these lines mention the partition at all, although I am not sure if not something gets lost because /var/log is not writable:

EXT3-fs (sda5): mounted filesystem with writeback data mode</code>  
EXT3-fs (sda5): using internal journal

The line in /etc/fstab looks like this:

/dev/sda5 / ext3 noatime 0 1

I am using the kernel 2.6.34-gentoo-r6 (the same problem existed with a previous 2.6.31 kernel). I have created it using genkernel 3.4.10.906. My grub configuration looks like this:

title=Gentoo Linux (2.6.34-gentoo-r6)
root (hd0,0)
kernel /kernel-genkernel-x86_64-2.6.34-gentoo-r6 root=/dev/ram0 real_root=/dev/sda5 vga=792 CONSOLE=/dev/tty1 resume=/dev/sda6
initrd /initramfs-genkernel-x86_64-2.6.34-gentoo-r6

Apart from that, I run baselayout 2.0.0 with openrc 0.6.3, if that is any important. sysvinit 2.87-r3 is also installed, I don’t know if it’s actually used.

Here is the output of dumpe2fs:

Filesystem volume name:   hd-root
Last mounted on:          <not available>
Filesystem UUID:          387432ca-2464-4c61-ba15-11c4af1c0418
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super large_file
Filesystem flags:         signed_directory_hash 
Default mount options:    (none)
Filesystem state:         clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              1528912
Block count:              6104692
Reserved block count:     0
Free blocks:              413799
Free inodes:              674036
First block:              0
Block size:               4096
Fragment size:            4096
Reserved GDT blocks:      1022
Blocks per group:         32768
Fragments per group:      32768
Inodes per group:         8176
Inode blocks per group:   511
Filesystem created:       Tue Dec  9 14:48:56 2008
Last mount time:          Mon Sep 27 00:00:15 2010
Last write time:          Sun Sep 26 23:55:12 2010
Mount count:              39
Maximum mount count:      -1
Last checked:             Sun Sep 26 23:51:51 2010
Check interval:           0 (<none>)
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:               256
Journal inode:            8
First orphan inode:       698281
Default directory hash:   tea
Directory Hash Seed:      4229715b-4ad1-4285-940b-9960db1cb4e1
Journal backup:           inode blocks
Journal features:         journal_incompat_revoke
Journal size:             128M
Journal length:           32768
Journal sequence:         0x003d9991
Journal start:            1

I have no idea what could cause this problem. I cannot find any error messages, and searching the internet, I only find manuals how to deliberately mount the root filesystem read-

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2 Answers 2

up vote 3 down vote accepted

The solution for the problem is easier than expected. Appearantly in baselayout 2, there is a service called root that just remounts the root file-system read-write.

The reason why I didn’t have this service in my boot runlevel is probably that I have updated to baselayout 2 rather early, and probably this service (and several others) was introduced later. The following services are in my boot runlevel now, and everything works:

bootmisc
consolefont
device-mapper
dmcrypt
fsck
hostname
hwclock
keymaps
localmount
modules
net.lo
netmount
network
procfs
root
svscan
swap
sysctl
sysfs
termencoding
urandom
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What is your baselayout version?

emerge -pv baselayout udev

Where is ext3 support located? In kernel, or module via initrd?

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Baselayout is 2.0.0, udev is 151-r4. ext3 seems to be in kernel: CONFIG_EXT3_FS=y –  cdauth Sep 27 '10 at 16:57
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