What is mount point in linux

What is a mount point in Linux/Unix?

Mounting takes place before a computer can use any kind of storage device (such as a hard drive, CD-ROM, or network share). The user or their operating system must make it accessible through the computer’s file system. A user can only access files on mounted media —From Wikipedia.

From the above statement only a geek can understand what a mount point is and for the people who are new to Linux/Unix cannot understand it in one shot and they have to do a bit of research on it to understand. This post is for new people who are just going to learn disk management and Linux. All the advanced users can ignore this post if you people know the meaning of mount point in Linux.

So what actually a mount point is?

In simple words a mount point is a directory to access your data (files and folders) which is stored in your disks.

To understand a mount, we should know two more concepts

What is a partition?
What is formatting?

A partition is a slice of a hard disk to write data into it. There are many advantages in creating partitions such as protection from data corruptions by isolating each partition from one another, systematic writing data to disks, even sometimes writing and reading is fast when we create partitions.

Formatting is a concept on how we write data onto disks. Data can be written in many ways with different meta data added to each chunk of data written to disk for security, reductions in disk space wastage, etc.

Once formatting is done on a partition, we can write data on the partition. To access that partition we link the partition to a directory in our machine so that if we go to that directory we can access all the data stored in that partition. This linking of partition with a directory is called as mounting or mount point.

Still did not get the mount concept?

Let us read a farmer story who distributed his uncultivable land to his children and what they did from it.

There is a former who thought of distributing his whole barren land of 25 Hectares to his three children, he distributed as below.

Child 1 : John got eight hectares of land.

Child 2: Barbie got 13 hectares of land.

Child 3 : Steve got four hectares of land.

Now the former children planned for improving their respective lands and started ploughing depending on the crops they are going to cultivates.

John wants to cultivate Oranges.

Barbi wants to cultivate Mangos.

Steve wants to cultivate corn.

For these crops/fruit tree cultivation they require to plough differently to suite their crops. As shown below diagram for cultivating Mangos ploughing is different from cultivating corn. Once this is done they sow their respective crop plants in their lands.

As crops are grown they should be protected from intruders and they arranged a fence around their lands and created an entry point to each of their lands with a gate.

So if anyone to access their lands they have to enter through these gates and get the fruit’s/corn from the land.

The analogy of this story to our disk management is as below.

Farmers land is equal to entire disk
Slices which farmer given to his children is called as partitions
Ploughing land for cultivating crops is called as formatting.
Planting trees and crops are called as writing data to disks/partitions.
Protecting the grown crops and trees by arranging a gate is called mounting.

Some FAQ’s related to mount in Linux/Unix:

Q. I lost my mount point,is my data lost in that partition?

You just lost your access point not the data. To access your partition mount your partition on other directory.

Q. I am M$ windows person and I do not see any mount point stuff, can you explain where is my mount point?

M$ hidden the concept of mounting. The drives in windows is called as mount points and it starts from C drive and ends with Z drive. And, why we do not have A and B drives have all different story.

Q How can I find mounted partitions in my machine?

​Hope this helps new commers to Linux will understand this.

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What mount points exist on a typical Linux system?

I have 2 questions.

1. During Linux installation we specify memory space for 2 mount points — root and swap. Are there any other mount points created without the users notice?
2. Is this statement correct: «mounting comes into the picture only when dealing with different partitions. i.e, you cannot mount, say, /proc unless it’s a different partition»?

2 Answers 2

There are misconceptions behind your questions.

1. Swap is not mounted.
2. Mounting isn’t limited to partitions.

Partitions

A partition is a slice¹ of disk space that’s devoted to a particular purpose. Here are some common purposes for partitions.

• A filesystem, i.e. files organized as a directory tree and stored in a format such as ext2, ext3, FFS, FAT, NTFS, …
• Swap space, i.e. disk space used for paging (and storing hibernation images).
• Direct application access. Some databases store their data directly on a partition rather than on a filesystem to gain a little performance. (A filesystem is a kind of database anyway.)
• A container for other partitions. For example, a PC extended partition, or a disk slice containing BSD partitions, or an LVM physical volume (containing eventually logical volumes which can themselves be considered partitions), …

Filesystems

Filesystems present information in a hierarchical structure. Here are some common kinds of filesystems:

• Disk-backed filesystems, such as ext2, ext3, FFS, FAT, NTFS, …
  • The backing need not be directly on a disk partition, as seen above. For example, this could be an LVM logical volume, or a loop mount.
• Memory-backed filesystems, such as Solaris and Linux’s tmpfs.
• Filesystems that present information from the kernel, such as proc and sysfs on Linux.
• Network filesystems, such as NFS, Samba, …
• Application-backed filesystems, of which FUSE has a large collection. Application-backed filesystems can do just about anything: make an FTP server appear as a filesystem, give an alternate view of a filesystem where file names are case-insensitive or converted to a different encoding, show archive contents as if they were directories, …

Mounting

Unix presents files in a single hierarchy, usually called “the filesystem” (but in this answer I’ll not use the word “filesystem” in this sense to keep confusion down). Individual filesystems must be grafted onto that hierarchy in order to access them.³

You make a filesystem accessible by mounting it. Mounting associates the root directory of the filesystem you’re mounting with a existing directory in the file hierarchy. A directory that has such an association is known as a mount point.

• For example, the root filesystem is mounted at boot time (before the kernel starts any process²) to the / directory.
• The proc filesystem over which some unix variants such as Solaris and Linux expose information about processes is mounted on /proc , so that /proc/42/environ designates the file /42/environ on the proc filesystem, which (on Linux, at least) contains a read-only view of the environment of process number 42.
• If you have a separate filesystem e.g. for /home , then /home/john/myfile.txt designates the file whose path is /john/myfile.txt from the root of the home filesystem.

Under Linux, it’s possible for the same filesystem to be accessible through more than one path, thanks to bind mounts.

A typical Linux filesystems has many mounted filesystems. (This is an example; different distributions, versions and setups will lead to different filesystems being mounted.)

• / : the root filesystem, mounted before the kernel loads the first process. The bootloader tells the kernel what to use as the root filesystem (it’s usually a disk partition but could be something else such as an NFS export).
• /proc : the proc filessytem, with process and kernel information.
• /sys : the sysfs filesystem, with information about hardware devices.
• /dev : an in-memory filesystem where device files are automatically created by udev based on available hardware.
• /dev/pts : a special-purpose filesystem containing device files for running terminal emulators.
• /dev/shm : an in-memory filesystem used for internal purposes by the system’s standard library.
• Depending on what system components you have running, you may see other special-purpose filesystems such as binfmt_misc (used by the foreign executable file format kernel subsystem), fusectl (used by FUSE), nfsd (used by the kernel NFS server), …
• Any filesystem explicitly mentioned in /etc/fstab (and not marked noauto ) is mounted as part of the boot process.
• Any filesystem automatically mounted by HAL (or equivalent functionality) following the insertion of a removable device such as a USB key.
• Any filesystem explicitly mounted with the mount command.

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What does ‘mount point’ mean in a Linux installer?

While installing Linux, it asks for a ‘mount point’ selection. I gave it / , but I don’t know the exact meaning and aim of this.

Also, now I want to create one more mount point, /home in my machine with the already installed Linux with mount point / . Is it possible to do that from my current Linux install? If yes, what are the steps/commands?

My understanding of ‘mount point’ is, when I need to preserve my /home contents in a safer way that it won’t get deleted if my current Linux get corrupted. For example, by detaching and connecting the hard disk from the machine with corrupted Linux to a new Linux machine, I should get my /home content.

1 Answer 1

The mount point specifies at which location in the directory hierarchy a device or disk partition appears.

If you want to move /home to a new partition, you have to create a new partition for it, say /dev/sda4 and format it, e.g. with ext4. Creating partitions and formatting them can be comfortably done using e.g. gparted.

Then you have to copy the old contents to the new partition and modify /etc/fstab so /home points to the new partition. As root do something like this after having the partition created and formatted. Again, I assume /dev/sda4 for the partition, this is just an example and you have to use your real partition device:

Now check if your system is still working correctly. If it does, add a line like this to /etc/fstab :

and delete the backup in /old_home

if however you find that something went wrong, you can move back by not adding respectively removing the above line in /etc/fstab and doing as root

Источник

What is mount point in linux

3.1.2.3. Mount points All partitions are attached to the system via a mount point. The mount point defines the place of a particular data set in the file system. Usually, all partitions are connected through the root partition. On this partition, which is indicated with the slash (/), directories are created. These empty directories will be the starting point of the partitions that are attached to them. An example: given a partition that holds the following directories: We want to attach this partition in the filesystem in a directory called /opt/media. In order to do this, the system administrator has to make sure that the directory /opt/media exists on the system. Preferably, it should be an empty directory. How this is done is explained later on in this chapter. Then, using the mount command, the administrator can attach the partition to the system. When you look at the content of the formerly empty directory /opt/media, it will contain the files and directories that are on the mounted medium (hard disk or partition of a hard disk, CD, DVD, flash card, USB or other storage device). During system startup, all the partitions are thus mounted, as described in the file /etc/fstab. Some partitions are not mounted by default, for instance if they are not constantly connected to the system, such like the storage used by your digital camera. If well configured, the device will be mounted as soon as the system notices that it is connected, or it can be user-mountable, i.e. you don’t need to be system administrator to attach and detach the device to and from the system. There is an example in Section 9.3. On a running system, information about the partitions and their mount points can be displayed using the df command (which stands for disk full or disk free). In Linux, df is the GNU version, and supports the -h or human readable option which greatly improves readability. Note that commercial UNIX machines commonly have their own versions of df and many other commands. Their behavior is usually the same, though GNU versions of common tools often have more and better features. The df command only displays information about active non-swap partitions. These can include partitions from other networked systems, like in the example below where the home directories are mounted from a file server on the network, a situation often encountered in corporate environments. Источник Оцените статью Вам также может понравиться Windows или Linux: Что лучше выбрать? Есть много причин выбирать между Windows и Linux, но Файл владелец изменить linux Команда Chown в Linux Chown Command in Linux (File Установка шлюза по умолчанию linux Настройка сети вручную Содержание Краткое описание Чем разбить диск для linux ИТ База знаний Курс по Asterisk Полезно — Узнать IP — Правообладателям Политика конфиденциальности Контакты