Linux data recovery after file system corruption

In Linux OS all the information about the file required during the booting of the system are stored At the Root File system,
This file system is saved on the same partition where the root directory is situated. Corruption in this file system can be due to the following reasons

1) Improper system shutdown
2) OS malfunction
3) virus infection
4) Power Surge
5) human errors like accidental deletion

In most of the cases, the system becomes unbootable, resulting in inaccessibility of hard disk data. To get past root file system corruption, a user needs to run it by running FSCK command manually. However, if the corruption persists even after running the FSCK command, then the user needs to opt for a third-party Data Recovery Linux application.

To explain the above case, consider a practical scenario where you encounter the underneath error message while booting your Linux system:

“*Checking root file system…
/contains a file system with errors, check forced
/:
Duplicate or bad block in use!
/: Multiply-claimed block(s) in inode 8: 1024
/: Multiply-claimed block(s) in inode 81297: 1024
/: (There are 1 inodes containing multiply-claimed blocks.)
?: File (inode #8, mod time Mon Dec 26 21:40:14 2005) has 1 multiply-claimed block(s), shared with 1 file(s):
/: /bin/zless (inode #81297, mod time Fri Jul 8 22:19:49 2005)
/:
/: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY
(i.e., witjout -a or -p options)

*fsck failed. Please repair manually and reboot”
The error message makes the system unbootable and the hard disk data inaccessible.

Cause Of the above error message:

As stated in the error message, the root file is damaged or corrupted.

Resolution of the above problem is given below:

To get rid of the above error message, you will need to follow the steps given below

1) Run FSCK command manually.

2) If the command fails, restore the data from an up-to-date backup.

3) If no backup available, then format the hard drive and reinstall the operating system. To recover formatted files post re-installation, use an effective Linux data Recovery application.

A Linux data Recovery tool uses effective recovery techniques to recover lost file/data from a formatted Linux system.

linux recovery after data loss due to virtual drive

A virtual drive is just like general hard drive in a PC,in actual it is the emulation of a hard disk where a traditional Linux file system resides on physical drive partition. Because the virtual drive offers more flexibility of data storage, users consider converting all their file system divisions to the virtual disks. After converting divisions to virtual disk, you can access them only through virtual disk nodes.

To migrate to a virtual drive from system based divisions, unmount your Linux file system on the division . Then create simple virtual drive for every division with the help of Virtual Drive Manager. Divisions are allocated to the virtual disks. When the Linux file system is in the simple virtual drive pattern, migration to another array pattern could be wrong without removing the hard drive. Always make sure that the divisions are not accessed during migration process.


To simply convert file system divisions to virtual drive the following steps are to be followed:

1) Unmount the file system on divisions

2) For every drive division, choose New from drive menu, insert a simple virtual drive and allocate divisions to virtual drive. It overlays every division with simple virtual drive.

3) For every drive division, choose Modify from Disk Menu and migrate simple virtual drive to desired RAID* type.

4) Use File System Manager for updating the information of mounted on the file system. Replace the divvy** device nodes of file system with their virtual drive ones.

In this way, you easily convert your hard drive to a virtual disk and can take benefit of greater flexibility and improved performance. But if the conversion process gets interrupted by any of the reasons like sudden power failure, irresponsive OS, unexpected system shutdown or restart because of already mounted volume etc. we may face serious problems of data loss.

Not all Linux systems are licensed to use Virtual Drive Manager. Unfortunately, if your system isn’t licensed and you are trying to convert your partitions, Virtual Drive Manager exits with some error messages. All these situations put you in trouble of data loss and you need to perform Linux Data Recovery to overcome this problem. The recovery in Linux can easily be achieved using third party applications, known as data recovery Linux software. Linux recovery software are particularly designed to meet recovery requirements of all Linux users.

Ext4 recovery: Resolving Error in Ext4 Linux File System

Ext4 or Fourth Extended file system is latest file system in linux. It is widely adopted as the successor of Ext3 file system as it has a number of powerful advance features. These features improve performs, stability, integrity,security and consistency of our PC. However, in some cases, your Ext4 file system volumes becomes difficult to mount or inaccessible due to Some error in the file system. Such situations cause data loss and need Linux Recovery to be sorted out.

In a practical scenario, you may encounter freezing of the system, while working on your Linux computer. The system may stop responding . At the same time, you can not mount your Ext4 file system volume and the file system looks to be damaged. When you try to mount the Linux volume,below error message is displayed:

A) "mount: wrong fs type, bad option, bad superblock on /dev/sdb1, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so"

When you try dmesg, it gives you further error message:

A) "EXT4-fs: ext4_check_descriptors: Block bitmap for group 0 not in group (block 727012683)! EXT4-fs: group descriptors corrupted!"

At this point, when you run fsck utility to perform linux data recovery by fixing the issue, you encounter a long error that may include messages like:

0) "Inode table for group 0 is not in group. (block 1236188664)

WARNINGS

SEVERE DATA LOSS POSSIBLE. Relocate? No

0) Inode table for group 1 is not in group. (block 600148394)

WARNING: SEVERE DATA LOSS POSSIBLE. Relocate? no"

As stated in the above error message, you may encounter critical data loss conditions if you relocate the Inode table. Backup proves a great help in such situations. However, if the backup is not available or else it is not updated at all, Data recovery Linux Software comes for your rescue.

Data Loss due to "Linux Unified Key Setup" Encryption

Protecting your Secret data from unauthorized access is a major concern for business houses. To prevent unauthorized access of your confidential data, Linux provides "Linux Unified Key Setup" its a data encryption technique. The LUKS is a hard disk encryption standard that guards your data by offering the standard "on-disk-format". It also avoids the possibility data loss due to sabotage and need of Linux data Recovery.

The "Linux Unified Key Setup" determines a platform-independent encryption standard to use in several tools. It not only provides interoperability and compatibility with many different applications, but also insures that password management is applied efficiently in a secured and documented manner.

Although, LUKS (Linux Unified Key Setup) is a pretty useful standard to encrypt your confidential data and information, but under some circumstances it may lead to data loss. You may come across data loss if you perform any of the below operations on your Linux hard disk that uses Linux Unified Key setup encryption:

1) Boot your system with any of the itoi, iswsusp, or is2 matching arguments to appropriate kernel in init script.

2) Boot the kernel with noresume, noresume2 options or non-matching hibernating Linux kernel and resume from the previous image on next boot.

3) Try to resume the process with different Linux kernel. If new kernel has the suspend2 support, you encounter a warning message bout the version mismatch. At this point, you should press Shift key for rebooting the system. You must not continue booting the system. Resuming the system with different kernel may crash or corrupt the system and may lead to file system corruption.

4) Mount partitions, which are mounted during suspended and then you try to resume them.

In such situations, backup proves a real help to preform Linux Data Recovery. You can easily restore your valuable data from backup. However, if the backup not updated or corrupted, you are required to opt for third-party Linux recovery solutions.

The Linux data Recovery Software enables you to scan entire hard disk through its efficient scanning techniques and extract all lost, missing,and inaccessible file. They have simple and rich graphical user interface and thus allow us to carry out Linux Recovery operations on your own. The applications preserve integrity of our data as they have read-only and non-destructive conduct.

File system Journaling And Ext3 recovery

Most of the File systems in Linux Like ext3,ext4 support journaling in file system and thus they are less prone to corruption. But as all problems can’t always be ruled out, a Linux volume can get corrupt for many reasons. Though you can delete the corrupted volume to resolve such issues, but Linux Recovery is always a primary concern to save all data .

Here is one of the problems that a Linux generally experiences while mounting a volume. Consider you are a Linux user. You successfully shutdown your computer, but it fails to boot when you try it again it shows the below error report on the screen:

1).EXT3-fs error (device dm-0) ext3_check_descriptor: Block bitmap for

2)mount: error 2 mounting none

3)EXT3-fs group descriptors corrupted

4) mount: error 22 mounting ext3

5) group 0 not in group (block 41471)

6) switchroot: /initrd/dev failed: 2

7) Kernel panic not syncing: Attempt to kill init

This error report is preceded with the general information regarding mounting of the volume.

Reasons

The Above errors most likely occur because of journal file corruption in ext3 File system logical volume.

Ext3 is a journaled file system that keeps record of all the changes in a journal file. This file is helpful in bringing the file system back to its original state after any system crash. Damage to journal file can cause serious Problems

Solution

In order to resolve the discussed issue, you should follow the below mentioned steps:

• Boot the system with the help of system Rescue CD

• After booting the System, you can run fsck.ext3 command to repair the corrupted ext3 volume

However, if the problem persists, the only solution is to recreate the volume and restore lost data from the recent backup.

There are situations when data backup is not in usable state. To deal with such issues, you can use Ext3 Recovery software. These are perfect Linux Recovery tools designed to scan a corrupted or deleted Linux volume and extract possible data to a safer location.

Ext3 recovery and no journal on file system error

Ext3 is a journaled file system and maintains a journal file to prevent metadata corruption. Due to its wide testing base and relative simplicity, the file system is considered to be Quiet Stable if compared it with other file systems,but it is not completely immune to crashes. sometimes you might receive some errors when using a Ext3 formatted disk, you may receive error that system doesn’t find any journal on the file system. As a solution, you have to reinstall the system. In such situations, you need to check the status of your backup whether it is working and updated recently or not. But if you observe any backup related issues, Linux recovery tools are to be used .

For an instance, while attempting to mount your Linux based hard disk, you might come across the following error message:

“ext3: no journal on file system”

The system fails to boot and Data becomes in accessible. If you boot the system somehow, you may observe that some of the files and folders are missing from the system.


Among various reasons possible for this behavior, some of them are as below:

· File system is severely corrupted

· No or corrupted journal file

· You have recently updated the kernel but the process ended abruptly


To try resolving the issue, follow these steps:

· Boot the Machine using an installation drive and access the Rescue Mode. Mount the existing installation and reinstall the improperly installed kernel package

· journal file can be created by executing the below command:

tune2fs -j /dev/yourpartitionid

· If above measures fail, try repairing the file using the command "fsck". Boot the system using an installation disc and access the Rescue Mode. While making the system unmounted, run fsck for all the hard disk partitions except the swap partition.

If these measures don’t help and your data still is not accessible, use Linux recovery software for successfully recovering your lost data. Linux data Recovery applications incorporate high end scanning algorithms to scan the logically crashed media to recover data while maintaining their integrity.

Linux recovery : Data loss due to Damaged Hard Drive

In Linux OS, the hard disk volume is mounted by the disk labels, in place of the device paths. It is a very effective approach as the disk path and name can get changed when you boot your system and so can create a number of Errors in your system. Therefore, the labels are assigned to Linux volumes so that they can be mounted at correct place But in some situations, the disks can not be mounted and accessed due to disk label corruption and you face critical data loss conditions. In order to extract lost data in such situations, Linux recovery Software's are required.

The drive label is very important data structure for accessing a Linux hard disk volume. All the entires for volumes to be mounted during boot time are stored in (/etc/fstab) file. When drive labels get damaged, Linux volumes fails to mount and thus all your important data becomes inaccessible.

This issue may occur during the booting of the system. When the system is shut down in improper way, fsck runs automatically at startup. This command-line utility checks integrity of hard disk and file system to detect and repair errors. However incomplete or improper processing of this tool may increase the chances of corruption in file systems. This behavior of Linux OS needs Linux data recovery tool to be handled.

When you run the fdisk command to change hard disk partition table, following error message may occur and the process gets terminated:

“Warning: invalid flag 0×0000 of partition table 4 will be corrected by w(rite)”

The above error indicates that there is a volume label corruption and due to the same, volume can not be either seen or accessed. In such cases, backup proves as real help to restore your data from affected storage media. But in case if the backup is not available, Linux data Recovery Software are needed for extracting lost data.

These applications are developed to scan the whole hard disk throughly and extract all inaccessible,lost and missing data from the system.