Understanding Linux file system sorts

Chances are you’ll not spend a lot time considering the traits of the file programs in your Linux system, however the variations between the varied file system sorts could be each attention-grabbing and extremely related. This text explains instructions that you need to use to confirm your file system sorts and describes their variations.

Instructions that report file system sorts

There are a variety of Linux instructions that can show file system sorts together with the file system names, mount factors and such. Some can even show sizes and accessible disk area.

Utilizing df -Th

The df command with the “T” (present file system kind) and “h” (use human-friendly sizes) choices supplies a really helpful have a look at the file programs on a Linux system. This is an instance:

$ df -Th
Filesystem     Kind      Measurement  Used Avail Use% Mounted on
devtmpfs       devtmpfs  4.0M     0  4.0M   0% /dev
tmpfs          tmpfs     2.9G     0  2.9G   0% /dev/shm
tmpfs          tmpfs     1.2G  1.7M  1.2G   1% /run
/dev/sda2      btrfs     111G   11G  100G  10% /
tmpfs          tmpfs     2.9G   56K  2.9G   1% /tmp
/dev/sda2      btrfs     111G   11G  100G  10% /dwelling
/dev/sda1      ext4      974M  330M  577M  37% /boot
/dev/sdb1      ext4      427G   71G  334G  18% /apps
tmpfs          tmpfs     593M  128K  593M   1% /run/person/1000

Discover that the main points embrace mount factors, sizes, used and accessible area.

Utilizing fsck

You should use the fsck (file system examine) command to report on a specific file system as proven within the instance beneath. This pattern command reveals that the /dev/sda1 disk partition comprises an ext4 file system.

$ fsck -N /dev/sda1
fsck from util-linux 2.37.4
[/usr/sbin/fsck.ext4 (1) -- /boot] fsck.ext4 /dev/sda1 

Utilizing lsblk

The lsblk (listing block gadgets) command shows data on block gadgets (storage gadgets that maintain information within the type of blocks) – each arduous drives and strong state drives. It supplies file system kind data alongside different information – the file system model, the UUID (distinctive identifier) and mount level, together with particulars on how a lot area is accessible and what number of the allotted area is in use.

$ lsblk -f /dev/sda1
NAME FSTYPE FSVER LABEL UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
sda1 ext4   1.0         417d867b-270d-4ceb-a3e1-58b9a5f5c4c4  576.8M    34% /boot

Utilizing the mount command

The mount command beneath reveals file system sorts for mounted file programs (fifth string) together with many extra particulars.

$ mount | grep /dev
devtmpfs on /dev kind devtmpfs (rw,nosuid,seclabel,measurement=4096k,nr_inodes=131072,mode=755,inode64)
tmpfs on /dev/shm kind tmpfs (rw,nosuid,nodev,seclabel,inode64)
devpts on /dev/pts kind devpts (rw,nosuid,noexec,relatime,seclabel,gid=5,mode=620,ptmxmode=000)
/dev/sda2 on / kind btrfs (rw,relatime,seclabel,compress=zstd:1,ssd,space_cache,subvolid=257,subvol=/root)
hugetlbfs on /dev/hugepages kind hugetlbfs (rw,relatime,seclabel,pagesize=2M)
mqueue on /dev/mqueue kind mqueue (rw,nosuid,nodev,noexec,relatime,seclabel)
/dev/sda2 on /dwelling kind btrfs (rw,relatime,seclabel,compress=zstd:1,ssd,space_cache,subvolid=256,subvol=/dwelling)
/dev/sda1 on /boot kind ext4 (rw,relatime,seclabel)
/dev/sdb1 on /apps kind ext4 (rw,relatime,seclabel)

To view only a listing of the file system sorts, use a command like this:

$ mount | grep "/dev" | awk '{print $5}' | kind | uniq
btrfs
devpts
devtmpfs
ext4
hugetlbfs
mqueue
tmpfs

Utilizing the file command

The file command with the -sL choices can be utilized to listing particulars for the file system related to a specific disk partition.

$ sudo file -sL /dev/sda1
/dev/sda1: Linux rev 1.0 ext4 file system information, UUID=417d867b-270d-4ceb-a3e1-58b9a5f5c4c4 (wants journal restoration) (extents) (64bit) (giant recordsdata) (large recordsdata)

File system sorts

Linux programs make use of quite a lot of file system sorts. Some have been constructed to interchange older file system sorts with quicker and extra dependable ones. Others serve some very explicit functions.

What’s ext4?

The ext4 file system is the 4th era ext file system. The primary, ext, was applied in April 1992 and was the primary file system created particularly for the Linux kernel. It was the primary implementation that used a digital file system (VFS) and will deal with file programs as much as 2 gigabytes (GB) in measurement.

Since ext, the opposite prolonged file programs – ext2, ext3 and ext4 – have been developed, every with enhancements over its predecessor.

What’s btrfs?

The btrfs file system is a “copy on write” (COW) file system. It’s usually pronounced “Higher F S”. It implements superior options with a concentrate on fault tolerance, self restore and painless administration.

What are tmpfs and devtmpfs?

Each tmpfs and devtmpfs file programs keep content material that’s really non permanent. Each are file programs which preserve all of their recordsdata in digital reminiscence. Every little thing is non permanent within the sense that no recordsdata can be created in your arduous drive. If you happen to have been to unmount such a file system, every thing saved in it might be misplaced.

They could look like mounted file programs, however they don’t seem to be. One function is to enhance boot time.

A devtmpfs file system makes use of automated gadget nodes populated by the kernel every time the system boots.

What’s hugetlbfs?

The hugetlbfs is an interface to the massive web page capabilities of the underlying {hardware}. It permits using all large web page sizes supported by the {hardware} and kernel.

What’s mqueue?

The mqueue file system kind supplies a light-weight buffer to quickly retailer messages and endpoints that enable software program elements to connect with the queue as a way to ship and obtain messages.

What’s devpts?

The devpts file system mounted as /dev/pts supplies pseudo-terminal assist for instruments like telnet and ssh. Have a look at its contents and you need to see one thing like this:

$ ls -l /dev/pts
complete 0
crw--w----. 1 shs  tty  136, 0 Apr  3 08:53 0
crw--w----. 1 shs  tty  136, 1 Apr 23 14:30 1
c---------. 1 root root   5, 2 Apr  3 08:07 ptmx

What’s XFS?

XFS is a 64-bit file system and, not less than in idea, can deal with file programs as giant as 8 exabytes. That is extremely giant. One exabyte equals a million terabytes. Oracle at the moment helps 100 terabytes, however that is nonetheless large. Discover that I did not use the phrase “solely”.

XFS supplies for fast restoration, scalability and pace. It provides the advantages of a journaling file system with out impacting efficiency. Journaling file programs preserve monitor of modifications not but dedicated to the file system by recording the objectives of these modifications.

XFS is the default file system in RHEL. As a result of it lays out recordsdata as extents, it’s much less weak to fragmentation than ext4. Crimson Hat recommends deploying XFS as your native file system except there are particular causes to do in any other case.

Wrap-up

The number of file programs on Linux programs serve many various functions and supply dependable and speedy responses to system operations.