How to repair corrupt superblock in ext2 file system

In the Linux systems, the ext2 (short for second extended file system) file system is used extensively by numerous users. This file system is very efficient when dealing with real large disk partitions. In addition, when the ext2 file system is mounted then all the information that is stored in the disk data structures is copied into the RAM of the system. 

Because of this, the Linux kernel is able to avoid numerous disk read operations. However, as nothing is perfect in this world the ext2 file system, too, is prone to corruption. In such cases, you should perform in-built methods to remove corruption and mount file system. However, in case you are unable to fix the problem then you should use a third-party Linux data recovery software to perform data recovery for Linux system.

Let us take an example. Consider a scenario wherein you have a Linux system having ext2-based file system. In this, when you try to mount the file system after a power outage you are unable to do so. An error message is displayed, that is:

“mount: wrong file system type, bad option, bad superblock, or too many mounted file systems”

Cause:
Such problems in mounting file system can occur due to corrupt ext2 file system especially the superblock.

Resolution:
To recover the problem of corrupt superblock, you should perform the following steps:

•  Search the superblock for the /dev/sda2 location.

•   Try to restore the file system using alternate superblock #xxx

Here, xxx is the location of the alternate superblock.

•   Now, try to mount the file system using the following command:

# mount /dev/sda2 /mnt

•    Try to mount the file system and check the files to see whether they are intact or not.

Such workarounds would be able to fix the superblock and you would be able to access the file system again. However, if the method does not succeed then you should use a third-party ext2 recovery software to recover the inaccessible data from the system. These Linux recovery tools have rich user interface that do not overwrite the existing file system while scanning the storage media. Also, the use of fast and sophisticated scanning algorithms ensures that the file system recovery is safe and secure.

Grub error and linux data recovery

Grand Unified Bootloader is a boot loader package from GNU with the implementation of multi boot specification. This enables an user to install multiple OS in a single PC and choose the one, which is to be run when the computer starts. 

GRUB facilitates a rich set of terminal commands that allow a user to view the hard drive partition details, alter partition settings, temporarily re-map the disk order, boot any user-defined configuration file and view the configuration of other boot loaders in GRUB supported file formats. Basically, GRUB errors indicate that the hard disk is suffering from errors and in those cases, if updated backup is not available, Linux file recovery software is the only safe option to get your valuable data back.

Taking a real life instance in account, while trying to boot, your Linux based machines gave an error and the data saved become inaccessible. The error may read as follows:

Error:
“GRUB Error 17 : Cannot mount selected partition”
Cause:
The above GRUB error message may occur due to following reasons:

If the partition, that has been requested, exists, but the file system type cannot be recognized by GRUB.
The mount point for the booting in the file /etc/fstab is pointing to an incorrect boot device. Note: '/etc/fstab' is the file that lists all the available disks, their partitions and conveys their initialization information when the mount command is used upon the devices.
Some of your Linux partition is suffering from file system corruption errors. However, GRUB has failed to recognize the error and started booting up that corrupted partition.

Solution:

If the file '/etc/fstab' that usually points to an incorrect boot partition, try to edit it as per the boot device.
Try to run 'fsck' command on your boot partition to fix the errors with your file system.
After trying the above measures, if the problem still persists, reformat the partition.

However, formatting will erase all the data from the partition and to restore the same, you need updated backup. If the backup is not available, or due to any reason, it failed to restore the data, Linux file recovery software is the only means that can recover and restore your valuable data into its original state.

These Linux recovery softwares are risk free with respect to data, as they don't further damage neither the data nor the storage media.

Understanding Linux OS and data loss in Linux

Linux is a powerful and user friendly operating system. Initially it was intended to offer a free or low-cost operating system for personal computer users. The Linux operating system represents a unique reputation as a very fast processing and efficient operating system. Linux consists of all UNIX components and some additional features like GUI, TCP/IP, X Window System and Emcas editor.

Linux operating system is technically sound and advance, highly configurable and secure operating system. Although the Linux is very secure and reliable operating system, but we all consider that it is man made software. Error may occur in any of the system or application software and it may affected by viruses. And it may cause data loss.

There are many reasons and failures of data loss in Linux operating system. Some of the most common reasons are as follows: -

Server Corruption Errors

File overwrites

Disk Reformatting

Accidental Deletion

Virus attack

The above listed error can happen at any time without any reason; it may cause data loss and may create any serious problem. It is really very critical situation for any organization. But it is not impossible to repair, recover or restore these lost data. You may overcome these problems and recover your lost data with the help of Linux data recovery software available in the market.

There is an extensive collection of Linux data recovery software existing in the market. These varies according to the error occurred and the type of file system used by the operating system.

Ext2 is the popular Linux file system. If any corruption is occurred in this file system, then it may cause data loss. If data loss is occurred in Ext2 file system, then you may recover it by using Linux Ext2 Recovery software. With this software, you can scan all your crashed hard drive and can restore the required data.

How to mount Linux in case the superblock is corrupted

In Linux system, memeory blocks are used to store all kinds of data. One of them is metadata. One of the most important metadata is superblock its main function is to keep all the details about the file system such asits block size. Hence, the superblock is one of the most components of the Linux system.However, it happens that your access to the superblock is blocked, resulting into disabling of mounting of the file system.

Consider a scenario when you fails to mount your ext3-based Linux system. the below message is displayed

"/dev/sda2: Input/output error
mount: /dev/sda2: fails to read superblock"

Reason:

The main reason behind this error is that the system files are damaged. Because of this, you fails to mount system files.

Solution:

To resolve this issue, you should restore the primary superblock from the updated backup copies.

The following procedures need to be followed in this case:

    A)  Locate the superblock for the /dev/sda2 location.

    B)  Repair the file system using alternate superblock #abc

where, abc is the location of the new superblock.

  C) Mount the System file using the following mount command:

# mount /dev/sda2 /mnt

    D) Finaly try to browse the file system and check if you are able to view all the files or not.

However, if you still fails to mount the file system then the only option available with you is to use a third-party Linux recovery software to recover the inaccessible data.

Linux data Recovery: when faced with error due to dual booting

In dual booting two different OS are installed on a single hard dsiks, enabling us boot from either of the two OS the whole process of dual booting is done with the help of system loader it is a program which allows us to have dual booting of the system. Generally  this procedure is done with the combination of Linux and Windows

The dual booting allows us to use functions and features of both of the OS on a single computer. Dual boot systems are normally used by programmers and testers.

Even though the whole process of dual booting is very important but sometimes this can cause several problems. A minor mistake here and there while making a dual boot system can lead to the serious issue.The common mistake is selecting “prepare hard drive” option which appears when you install Windows OS on a Linux system, in order to make it multi boot .

When this option is used, all the hard disk partitions and stored data gets deleted. After that new partitions are created and the OS is installed. When the installation completes,blank hard disk without any OS and data is whats remains. Everything, which was previously stored on the hard disk, will be deleted. In such situations, it is very important to recover all your precious data from the formatted hard disk to save you and your business.

What to do when superblock is corrupted in linux?

Superblock is one of the common meta data structures,and its corruption may lead to inaccessibility of the hard drive and need of a good Linux data recovery tool arises to recover back your data. Linux recovery becomes even more essential when your hard drive becomes inaccessible and you fails to understand either the error message or the cause of it.

Superblock corruption is one of the many possible errors like intrusion of virus/malware,partition table corruption  or file system corruption etc. In a LINUX hard disk, the partition is subdivided into multiple file system blocks. Most blocks store user data and some blocks store information of the file system itself or the meta data.

Scenario:
If you are trying to boot your PC, and encounter a serious error where the whole data stored in your hard drive becomes inaccessible. The error message being displayed may read as follows:

Error:
“The filesystem size is 12453462 blocks
The physical size of the device is 10093482 blocks
Either the superblock or the partition table is likely to be corrupt”

After receiving this error, when you manually try to run the command FSCK to resolve the above mentioned issue, you finds another message (error)  which reads as follows:

“Error reading block 10125318
while doing inode scan. Ignore error?

   Error reading block 10125319
while doing inode scan. Ignore error?”

Cause:
The primary reason behind these error messages is either the corruption of the partition table or the corruption of superblock.

Resolution:
·     Unmount all the partitions using the command ‘unmount-a’ .
·     Choose the alternate superblock that is used to be with the operating system and mount the file system.
·     Try to repair the corrupted hard drive partitions using the command 'e2fsck' command.
·     If the above measure fails to repair the hard drive partition, try to recreate all the partitions.

Recreating the partition will erase all the previously saved data in the hard disk and to recover them back, you need a powerful Linux data recovery tool.

Linux File Recovery Using Ext2 file Recovery Software

Unintentional deletion is one of the most common reasons of data loss as it is a very common user mistake. You may unintentionally remove some important files from Ext2 file system volume of Linux hard disk to free up the disk space and then realize their significance to your business. Most of the computer users think that the file is gone forever, once you deleted it. However, this is not the fact. The file is still there on your hard disk, but you can not access it because its file system entry is removed. In such cases, Linux file recovery proves to be a great help to get your precious files back.

In order to ensure successful recovery of lost or deleted files from Linux hard disk, first of all you should unmount file system. It minimizes the possibilities of overwriting the deleted file while trying to retrieve it. When you store a new file on the hard drive after deleting a file, operating system may overwrite the previously deleted file and make it impossible to recover the lost linux file.

If you are unable to unmount the Ext2 file system, because you have deleted the file from root file system, then you should shut down your system immediately. After that, remove the hard disk and attach the same to another Linux OS based computer. You should not install any software on the drive from which the file is deleted, particularly in case if the drive is almost full.

To handle such file loss situations and ensure perfect Ext2 file recovery, Linux OS provides you the following softwares:

1)   debugfs- The tool is useful in recovering deleted files, particularly if you are unable to unmount the Ext2 file system volume. The syntax for the debugfs is- /sbin/debugfs device. It lists all the deleted files on Ext2 file system volume.

2)   e2undel- It also works like debugfs, but features a simple and user-friendly GUI. The tool also provides some additional information to help you identify the deleted files.

In case the file is not recovered using the above methods, commercial Linux file recovery software come to your rescue. They thoroughly scan your Linux hard disk and extract all deleted, lost, missing, and inaccessible files from it. They perform quick, easy, and safe file recovery Linux and have an attractive user interface and a non-destructive behavior.

Linux Drive Recovery ::Volume Cannot Be Mounted Using Mount Command

All the Linux data files that are accessible Are placed in root directory and denoted as ‘/’, in an organized form. These data files might be spread out over various devices. The mount command in Linux OS allows you to attach a file system on a data storage media to the root directory. However, if the file system is faulty and you run fsck utility to fix the problem after mounting the disk using this command, severe file system corruption occurs. It causes critical data loss situations and calls for Linux recovery.

The mount command tells the Linux kernel to attach the file system found on your hard disk volume in the /dir directory. The previous owner, mode, and contents of the directory become invisible after mounting, and as long as the file system stays mounted, the /dir pathname refers to the root of file system on hard disk volume.

The following three types of invocations of mount command don’t actually mount the volume:

A))  Mount -h- It prints the help message on screen.
B))  Mount -V- This invocation prints the version string.
C))  Mount [-l] [-t type]- The option lists all the mounted file systems that are of type “type” on your Linux hard disk. The -l option adds labels (like ext2, ext3) in the listing.

In current versions of Linux OS, it is possible to mark the mount and submounts as private, shared, unbindable, or slave. The shared mount gives you an option to create mirrors of the mount.
Mount is an essential process for accessing data from any Linux hard disk volume. If the drive is not mountable, it cannot be accessed. Sometimes, when you try to mount a Linux volume, you come across the following error message that puts you in need of  Linux Volume recovery tool

“Wrong fs type, bad option, bad superblock on /dev/hda8, missing codepage or helper program, or other error. In some cases useful info is found in syslog – try dmesg | tail or so”
This problem is caused by dirty or corrupt file system. In such cases, you need to use Linux file Recovery software to get your important data back. The Linux recovery applications enable you to thoroughly scan the affected Linux hard disk using advanced scanning algorithms.

Ext2 file recovery from deleted files

Linux is one of the most used open-sourced OS that has carved its own niche among its trusted users thats because It's fast, easy-to-use, and reliable. Also, it is part of the Linux, Apache, MySQL and PHP stack that provides a lot of advantages to the developers and its users but it has one drawback that it does not have a Recycle or trash  Bin like Windows OS. So, after deletion of the file the recovery operations becomes difficulti. However, if you are unable to recover the deleted file then you should use a third-party data recovery toolto perform data recovery of linux systems.

Consider a scenario where you have an ext2-based Linux machine and you have accidentally deleted some files. Now, you want to recover the deleted files.

How to solve the issue:

To resolve this situation, you should perform data recovery of Linux system. And this can be done by following the below steps:

A) First of all, you should determine the partition from where the file was deleted. For this, you should use the "pwd" command in the shell console to know the working directory.

B)  Now you have to unmount the current directory using the unmount command.

C)  Now You should use the debugfs command.

D)  Now use the isdel command.

E) Now use the dump filename command.

F) Finally restart the system. The recovered files will be at user defined location.

However, if you still are not able to recover the deleted files, then you should use a third-party Ext2 file recovery software to do the needful. Such Ext2 Recovery tools are read-only in nature and are able to perform Linux recovery using fast yet sophisticated scanning algorithms.