All the active storages devices in Linux are part of the single file system starting at /.
The hard drive is identified by /dev/sda:
s identifier indicates that it is a sata drive
a indicates that it is the first drive (/dev/sdb would the the second drive if present)
the drive is divided into different volumes/partitions, each with its own ID mounted at a different location in the file system
First partition is /dev/sda1
Second partition is /dev/sda2, mounted at /boot/efi
Third partition is /dev/sda3, mounted at filesystem root /
Every file or directory that isn't in one of the subdirectory mount points, resides on the /dev/sda3 partition since it is at the filesystem root.
The virtual dvd drive is identified by the read-only /dev/sr0
Mounting Configuration
cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point> <type> <options> <dump> <pass>
# / was on /dev/sda3 during installation
UUID=2b17aaa3-594a-43eb-9c65-3b89ebb0bc05 / ext4 errors=remount-ro 0 1
# /boot/efi was on /dev/sda2 during installation
UUID=4704-6965 /boot/efi vfat umask=0077 0 1
/swapfile none swap sw 0 0
Each partition has a unique identifier UUID that the system uses.
mount
mount - command used to mount partitions, or shows the current mounted devices
mount
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
udev on /dev type devtmpfs (rw,nosuid,relatime,size=1975416k,nr_inodes=493854,mode=755,inode64)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,nodev,noexec,relatime,size=402020k,mode=755,inode64)
/dev/sda3 on / type ext4 (rw,relatime,errors=remount-ro)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,inode64)
tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k,inode64)
cgroup2 on /sys/fs/cgroup type cgroup2 (rw,nosuid,nodev,noexec,relatime,nsdelegate,memory_recursiveprot)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
bpf on /sys/fs/bpf type bpf (rw,nosuid,nodev,noexec,relatime,mode=700)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=29,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=15742)
tracefs on /sys/kernel/tracing type tracefs (rw,nosuid,nodev,noexec,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,nosuid,nodev,noexec,relatime)
mqueue on /dev/mqueue type mqueue (rw,nosuid,nodev,noexec,relatime)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,pagesize=2M)
fusectl on /sys/fs/fuse/connections type fusectl (rw,nosuid,nodev,noexec,relatime)
configfs on /sys/kernel/config type configfs (rw,nosuid,nodev,noexec,relatime)
none on /run/credentials/systemd-sysusers.service type ramfs (ro,nosuid,nodev,noexec,relatime,mode=700)
[...]
df
df - displays the disk file system space usage of all the mounted partitions
