What is rootfs?

Question

I'm a longtime Fedora user and I've just installed FC15. The new partition layout is confusing to me, as I'm used to the "plain vanilla" partitions that previous versions used.

[root@localhost ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
rootfs                7.9G  596M  6.9G   8% /
udev                  496M     0  496M   0% /dev
tmpfs                 502M     0  502M   0% /dev/shm
tmpfs                 502M  288K  501M   1% /run
/dev/mapper/vg00-lv00
                      7.9G  596M  6.9G   8% /
tmpfs                 502M     0  502M   0% /sys/fs/cgroup
tmpfs                 502M     0  502M   0% /media
/dev/sda1             194M   20M  165M  11% /boot
/dev/mapper/vg00-lv03
                      2.0G  312M  1.6G  17% /var
/dev/mapper/vg00-lv02
                       20G  172M   19G   1% /home

I understand that the tmpfs partitions are mounted from an internal RAM disk. But what is this new rootfs partition and why does it appear to be mounting / twice?

Never understood why Fedora needed so many partitions, especially on a single hard drive system — TheLQ, Jun 01 '11 at 20:50
These are not partitions. They are filesystems. The `df` tool operates in terms of mounted filesystems, and doesn't necessarily tell one anything at all (c.f. the LVM filesystems, here) about actual partitions on the disc. For _that_ one uses tools such as [`gdisk`](http://rodsbooks.com./gdisk/) and `gparted`. — JdeBP, Jun 01 '11 at 21:57
The default Fedora installation will just create the / filesystem plus the ramdisk ones. I created the /var and /home ones myself. — Barry Brown, Jun 03 '11 at 07:59
Similar on Super User: http://superuser.com/questions/576723/what-is-rootfs-and-what-can-you-do-with-it — Ciro Santilli OurBigBook.com, May 14 '15 at 20:55

score 19 · Answer 1 · edited Jan 23 '17 at 10:24

19

rootfs is a special tempfs image used in initram, and stays in this instance because you have an encrypted LVM setup. Normally, init would overwrite rootfs with the actual mounted / file system, but Fedora may not have that fixed with your setup. There is no harm in it.

see: http://www.kernel.org/doc/Documentation/filesystems/ramfs-rootfs-initramfs.txt

edited Jan 23 '17 at 10:24

Benoit Duffez

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answered Jun 01 '11 at 18:37

Bryan Agee

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score 3 · Answer 2 · edited Feb 19 '17 at 16:31

3

I think this is a side-effect of symlinking /etc/mtab to /proc/mounts as this forum post suggests.

edited Feb 19 '17 at 16:31

Bex

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answered Jun 01 '11 at 17:49

sciurus

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What is rootfs?

2 Answers2