how do i understand where a directory is mounted?

Question

Ubuntu / DigitalOcean

I have a drive that is almost full but I have mounted a storage device. But I can't tell if a particular directory is on the external device or not.

I thought I mounted the device at /mnt But perhaps it is further down:

$ df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            7.9G     0  7.9G   0% /dev
tmpfs           1.6G  161M  1.5G  11% /run
/dev/vda1        78G   73G  4.9G  94% /
tmpfs           7.9G   88K  7.9G   1% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           7.9G     0  7.9G   0% /sys/fs/cgroup
/dev/vda15      105M  3.4M  101M   4% /boot/efi
tmpfs           1.6G     0  1.6G   0% /run/user/0
/dev/sdb         99G   31G   64G  33% /mnt/bot-wiz-100



$ du -sh /mnt/*
31G /mnt/bot-wiz-100
53G /mnt/ext1

So it appears to me judging by sizes that the /mnt/ext1 is actually a path on the main drive, and NOT something mounted externally.

Also I'm confused how / can be more full than a subdirectory.

Filesystem      Size  Used Avail Use% Mounted on
/dev/vda1        78G   73G  4.9G  94% /
/dev/sdb         99G   31G   64G  33% /mnt/bot-wiz-100

I looked at mount and other commands but find them hard to parse.

https://askubuntu.com/questions/583909/how-do-i-check-where-devices-are-mounted

score 1 · Answer 1 · answered Aug 27 '18 at 03:05

To determine the underlying device, mount point, and size/fullness of a specific directory, pass a directory name to df:

$ df /usr/local/bin
Filesystem                1K-blocks     Used Available Use% Mounted on
/dev/mapper/mistress-root  20511996 14443432   5057692  75% /

So it appears to me judging by sizes that the /mnt/ext1 is actually a path on the main drive

You don't need to look at sizes for that; the df output you posted shows quite clearly that /mnt/ext1 is on the root mountpoint, while /dev/sdb (presumably the external storage) is mounted on /mnt/bot-wiz-100.

As for why "/ can be more full than a subdirectory", that's because the statistics shown are for each mounted device. There's no aggregation of statistics up the tree, because that would be unhelpful.

how do i understand where a directory is mounted?

1 Answers1