I just installed Arch Linux on a server machine with a LSI hardware RAID 5.

During the installation, I created (and cfdisk properly reports) three partitions:

sda1 (/,     131G)
sda2 (/boot,   1G)
sda5 (swap,    4G)

Everything seems to be working fine, except that the df command is showing strange output:

Filesystem   1K-blocks   Used Available Use% Mounted on
tmpfs        131G        2.8G   121G     3%   /tmp
/dev/sda2    955M         50M   860M     6%   /boot

Note that at this point, /dev/sda2 isn't actually mounted... However, /dev/sda1 (my root partition) is missing, although it's definitely mounted. The readings for tmpfs would be correct if they were labeled "/dev/sda1". Likewise, the mount command (and /etc/mtab) displays:

tmpfs on /tmp type tmpfs (rw,nosuid,nodev)
/dev/sda2 on /boot type ext4 (rw)

Furthermore, I have a device sda3 in /dev/ which cfdisk doesn't know about.

In short:

  • /dev/sda1 doesn't show up anywhere
  • /dev/sda2 shows up without being mounted
  • /dev/sda3 exists but doesn't show up in 'cfdisk' (and has never been created) or 'df'
  • tmpfs is showing stats for /dev/sda1

This may be related to another issue I encounter during boot, see Strange boot behaviour

Any ideas on how to solve this?

  • sda3 is probably the extended partition, which it seems cfdisk omits from its listing. – psusi Jun 1 '12 at 14:50

You are most likely inside a "chroot" shell. The installer has done something like this:

mount /dev/sda1 /target
chroot /target

The chroot command creates a shell where /target is /. In that environment, the installer did mount /boot. Since this environment is not the one that mounted /, it doesn't end up in /etc/mtab but /boot does. I would assume however that if /proc is mounted in this environment, /proc/mounts might see the / mount.

  • Hey, you're right, /proc/mounts does see the / mount! However, I have rebooted the machine several times since installation, so I wouldn't expect to end up in a chrooted environment during normal boot. Any ideas? – Philip Jun 1 '12 at 14:05
  • During boot, I also noticed strange behaviour, please see serverfault.com/questions/394721/strange-boot-behaviour I'm pretty confident that those two issues are somehow related. – Philip Jun 1 '12 at 14:16
  • no, i wouldn't expect this to be the case during a normal boot, I would "During the installation". This is the case even when booting to the installed system? – stew Jun 1 '12 at 14:35
  • Yes, it is. I boot the machine and it shows the behavior described above. – Philip Jun 1 '12 at 14:37

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