How to Run Safely E2fsck on a Live, Mounted File System in your Linux system without Facing Data Loss

File system corruption is a common issue faced by Linux users over and over again. This problem usually results due to sudden power failures, bugs in the Linux code, hardware issues, etc. Linux has an inbuilt tool 'e2fsck' that is responsible for verifying and checking the consistency of the ext2/ext3/ext4 family of file systems. In case of ext3 and ext4 file systems that use journaling, this program generally replays the journal and then terminates. 

In a majority of cases, the file system is marked as clean after the application of journal. However, if the superblock shows that the file system needs repair, 'e2fsck' will carry out further processing. If the 'e2gsck' tool fails to repair corruption in the file system, you need to use advanced Linux Data Recovery software.

It is not safe or recommended to run 'e2fsck' on a mounted file system. This may lead to disk corruption and subsequent data loss. To do this, you can try the following two methods:

I)       Try to take your system to a single user mode and then unmount it:

·         Run 'init' (process control initialization) command to switch to runlevel 1, i.e. single user mode.

# init 1

·         Now, unmount '/home' file system with the help of 'umount' command.

# umount /home
# umount /dev/sda

·         Run the fsck or e2fsck tool

# fsck /home

or

# fsck /dev/sda3

or

# e2fsck -y /dev/sda3

II)    Boot your Linux computer using the installation CD and switch to rescue mode:

·         If you have Cent OS/Fedora Core/RHEL Linux, boot from the installation disc and run the following command at the boot prompt:

boot: linux rescue nomount

·         Create a new node for your hard disk and partition 3:

# mknod /dev/sda
# mknod /dev/sda3
# fsck /dev/sda3

You can also do the following:

# e2fsck -y /dev/sda3

If 'e2fsck' fails to resolve your file system issues, you should take help of a professional data recovery Linux utility. These third-party tools have a knack of recovering every bit of your lost, deleted, or formatted data from Linux hard drives and volumes. They support Ext4, Ext3, Ext2, FAT32, FAT16, and FAT12 file systems. 

Some of these utilities also provide an option to create an clone or exact replica of your hard drive. Moreover, they include support for all commonly-used Linux distributions, such as Red Hat, SUSE, Debian, Caldera, Mandrake, etc. 

Advanced Linux Data Recovery Software

When any volume of your LINUX hard drive contains unnecessary data, which you do not want any more, you format it and store data afresh. Sometimes, due to operating system malfunction, file system corruption or any virus/malware infection, volumes get corrupted and cannot be accessed. In such cases, you need to format the troubled partitions/volumes, so that data can be stored and accessed normally. This is case, when you have to format the volume forcefully, which results in the loss of valuable data in the formatted partition. Apart from these, there are occasions, when you lose all your data because of any accidental formatting. In any such occasion, if you still want to recover your data back, you need to take the help of any linux recovery software.

The act of formatting is similar to deletion of data. In both these operations (Deletion and Formatting), the data from their location get removed and we fail to access them with any normal means. In case of deletion, the operating system simply removes the data from its source location, whereas in case of formatting, the data as well as the structure of the volume are removed by the OS. In both the cases, the operating system removes all entries of the deleted data and marks the memory location as free so that new data can be stored at the same location.

In this context, the interesting thing is that the operating system never completely erases the deleted or formatted data from the hard drive and even after such an operation, your seemingly lost data are very much present at their locations. If the lost or removed entries of the deleted/formatted data can be retrieved, then the data can be easily restored.

LINUX recovery software are developed with innovative techniques to find out the lost entries of files due to deletion or formatting of them. These utilities are efficient enough to read those lost entries and recover the files back. Moreover they are designed with completely read only approach and retrieve data in their original format, without any damage/modification neither to the data nor to the storage architecture of the drive.

Lost your Important Files in Linux?

Researches say that out of the many different reasons of data deletion, the most common cause is human mistake. Sometimes, it happens accidentally, whereas some other time, it is intentional. You were deleting some unwanted copies of photos, when mistakenly deleted the only copy of a memorable photograph. Similarly, you just deleted a folder and only after the deletion, realized that there was one important financial document in that deleted folder, which you need badly. While working on your LINUX system, such instances are not so uncommon and users do encounter them quite often. But, don’t worry! Even after such critical cases of data loss, you can still recover your data by using any good Linux data recovery software.

There are various instances of data deletion, including accidental deletion, intentional deletion of data or sabotage, deletion by virus attack etc. In earlier time, it was believed that once you deleted a data from the system, the data goes for ever and it can never be retrieved. But, one interesting truth regarding this myth is that recovery of a deleted piece of data is quite possible.

So, the question is what happens to the data that you deleted and how it can be recovered back? When you deleted a file from your LINUX system, the operating system removed all its entries from the system hard drive and marked the memory, allocated to the deleted data as free. But, remember that LINUX does not erase or overwrite the deleted data, until you save new files onto the same disk. Hence, if by any technique you can find out the removed entries of the deleted data and read them, the data can be recovered.

The LINUX recovery software do exactly the same. These software are developed with highly advanced scanning algorithms. When you run the software, these scanning algorithms dig your hard drive/volume in all possible ways and read the lost/removed entries. By using those lost entries, the software recovers the deleted or formatted data back.

These Linux data recovery software are absolutely read-only in their operations and never alter the structure or format of the data in the drive. Moreover, the utilities are developed with such user friendly user interfaces that they can be used by professional programmers as well as non-technical home users.

How to Recover Data after Encountering Error – GRUB 17

Error – GRUB 17: Recover data

The Grand Unified Bootloader or GRUB is a package from GNU that facilitates implementation of multi-boot operation. With GRUB, you can install more than one operating system on your LINUX based computer and have their benefits. GRUB also facilitates viewing various hard drive partitions, repartitioning, modifying partition settings etc. However, sometimes it flashes error messages indicating problems in the hard drive, following which all the data in the data become inaccessible. In such situations, you can execute any data recovery LINUX utility to recover the seemingly lost or inaccessible data back.

You tried to boot your LINUX system and the system became inaccessible after displaying a GRUB error message. The error message, you may have encountered can be read as -

“GRUB Error 17: Cannot mount selected partition”

There can be a number of possible reasons behind the occurrence of the above error message, such as:

Though the requested volume/partition exists, but GRUB fails to recognize the file system.
The boot device set in the file '/etc/fstab' is incorrect.

Note: '/etc/fstab' stores information regarding connected disks as well as their partitions and provides the same to the system, when any drive is mounted.

GRUB has tried to boot a partition with severe corruption or damage to the file system.

Solution:
The following work around may help you resolve the above issues:
If the file '/etc/fstab' has been found with incorrect boot partition, try to edit and provide the correct boot partition.
If the file system has been found to be damaged or corrupted, run the 'fsck' command-line utility to locate and fix the errors.

If both the above option fails to solve the problem, you need to format the drive and make fresh partitions. With partitioning, all your data in the drive gets lost and you have to restore them from an updated backup. In case, you do not have a valid backup, you can still retrieve the formatted data by running any LINUX data recovery software.

These linux data recovery software incorporates many advanced techniques to read the lost entries of the formatted files and successfully recover them back. These software are extremely read-only in nature and with interactive user interfaces, quite easy to use.

Discussing a particular case of Superblock corruption in Linux

Linux offers you a multi-platform, secure environment suitable for the entire open enterprise and providing features to help you excel in every aspect of competition. It offers a centralized administration to help you manage and make the best possible use of the Linux technology. When it comes to security, Linux is the most widely-accepted operating system because of its top-of-the-line security features. Despite having a range of user-specific benefits, using Linux has a few drawbacks. The Linux file system is often subject to damage or corruption due to various reasons, such as virus infection, hardware malfunction, operating system bugs, etc. As a consequence, the valuable data present on the hard drive becomes inaccessible. To overcome this problem, you need to go for Linux recovery through a reliable third-party utility.     

For instance, you may come across the following error while working using your Linux-based system:

“suse:/# chown -v ryan:ryan /mnt/hdc1
failed to change ownership of `/mnt/hdc1' to ryan:ryan
chown: changing ownership of `/mnt/hdc1': Operation not permitted
suse:/# chmod -v 777 /mnt/hdc1
mode of `/mnt/hdc1' changed to 0777 (rwxrwxrwx)
suse:/# ls -l /mnt/
total 16
drwxr-xr-x 4 root root 16384 1969-12-31 17:00 hdc1
suse:/#”

Causes:
One of the following reasons might be responsible for the above error:
Due to incorrect directory or file attributes, you are unable to change the permissions.
The root directory is damaged, making the disk structure unreadable.
The superblock in the underlying file system is corrupt.

Resolution:
You need to try the following steps to resolve the issue: 

Use the below given command to edit your user ID from the terminal as follows:
 sudo gedit /etc/fstab
In the 'options' section,  provide the following values
umask= 0000
uid= your UID value
gid= your GID value
Now, save the file and exit.
Execute the following command from the terminal
 'sudo umount -a'
Run the command 'sudo mount -a' from the terminal.

If the problem still persists, you should take help of a proficient data recovery Linux utility. These third-party tools carry out an in-depth scan of your hard drive to retrieve all lost, deleted, or inaccessible data without affecting its integrity and other important characteristics. They have a simple, interactive interface design to make recovery easy and facile for the end users. Moreover, they support all mainstream Linux distributions, including Red Hat, SUSE, Debian, Caldera, Mandrake, etc.

Explaining a case of kernel panic in Linux 4 system

While trying to boot your Linux 4 system, you might have seen this on your screen:

“ext2fs partition type 0x83. ....ext3-fs: journal inode is deleted....
mount: error 22 mounting ext3 error 2 mounting name switchroot:
mountfailed:22 umount/initrd/dev failed:2 kernel panic - not syncing.”

This error indicates that somehow the beginning of the hard disk has become corrupt. The inode table contains some bad blocks that also include an ext3 journal file’s inode. Although, it is not certain but seems as if the root file system is non-recoverable. If you have a map, you can easily find out other copies of the inode table on the disk. In case the data is present on other file systems, use a disaster recovery boot media or an installation media to boot the system and try to recover data on those file systems by first mounting them and then moving data to another file system or tape.

Data is a valuable asset and if your data is really confidential or critical, you can take help of a reliable data recovery services provider. It is worthwhile to avail good data recovery services, but still they do not guarantee a complete recovery as the disk may have been seriously damaged or crashed.

Another best alternative is to run consistency checks and then try to reformat the drive and reinstall the operating system. Now, after configuring your system, you need to create a bootable CD and backup the entire system on a reliable media. You can now easily use the bootable disc to boot and then restore the system. You should always perform full system backups and that too frequently. This will ensure that you do not lose too much data or if the data is really important, have incremental backups and save them to a different device.

Kernel panic is a serious problem and may occur on any platform that you use.      

Exploring the causes of Superblock corruption in Linux and the possible data loss

A Linux file system consists of blocks. Some blocks store user data or files, while the other blocks store the file system’s metadata. The blocks that contain metadata are called metadata structures. A superblock is the most fundamental metadata structure that includes information about the file system, such as file system type, size, status, information about other meta data structures, etc. This information is critical and sensitive. If a superblock gets damaged or corrupt, you may encounter serious data loss. To overcome this problem and recover all lost invaluable data, you need to go for Linux recovery through a reliable third-party utility.

Suppose you use a Linux-based PC. When you attempt to mount your file system, you may receive the following error message on your screen:

“/dev/sda2: Input/output error
mount: /dev/sda2: can't read superblock”

Cause:

The above error indicates that there is some corruption in the superblock. This corruption may be caused due to several reasons, such as virus infection, abnormal shutdown of the system, operating system bug, etc.

As a consequence, all your valuable data present on the hard drive would become inaccessible. At this stage, you may use an updated backup to restore all the lost or inaccessible data. However, if the backup is unavailable, you should follow the below mentioned resolution steps.

Resolution:

Linux maintains multiple copies of superblock in the file system. In case if a damage occurs to the primary superblock, you can use these backup copies to restore the corrupt superblock. To resolve the above problem, you need to mount the partition using different superblock:

• First determine the location of the alternate superblock using the command:

# dumpe2fs /dev/sda2 | grep superblock

You will get the output as shown below:

Primary superblock at 0, Group descriptors at 1-6

Backup superblock at 32768, Group descriptors at 32769-32774

• Now, try repairing the file system using the backup copy of the superblock as follows:

# fsck -b 32768 /dev/sda2

• Use ‘Mount’ to mount your file system:

# mount /dev/sda2 /mnt

If the problem still persists, you should take help of a competent data recovery Linux tool. These third-party software help you safely recover every piece of lost, deleted, or inaccessible data from any Linux-based system. They provide a rich and interactive interface that needs no technical expertise for its proper implementation. Moreover, they support Ext4, Ext3, Ext2, FAT32, FAT16, and FAT12 file systems.