The command can be used to make an exact image of the data from the dying hard drive and can be restored later on. However, under unfortunate incidents, the disk image refused to be mounted and it seems as if all your data is lost. These are the extreme conditions, where you have to think over technologies like Mac hard drive recovery or Mac recovery software.

Facts about ‘dd’ command:

This is a common piece of UNIX command with the purpose of copying and converting raw data. ‘dd’ is usually used to copy a specified number of bytes or blocks of data and similarly byte level conversion, such as EBCDIC to ASCII conversion. Though this command is used to backup the boot sector of a hard disk, still you can also use it to copy the entire partition or disk. ‘dd’ command copies the information about deleted and formatted data as it copies byte by byte, whereas the usual ‘cp’ command misses it. Moreover, this command can make a copy of the specified data irrespective of the data type or the file system.

The Problem: your data in the Mac OS X based volume is inaccessible and you have sensed some problem with your hard drive. You accessed your drive through your UNIX OS and made an image of your data by using the ‘dd’ command. Later, when you try to mount the image and restore the data on your Mac OS X, it showed an error message and stuck. The error message read as:

“No mountable file systems”

As the data image is refused to be mounted, you cannot restore the your data, through the image, you had made by the ‘dd’ command.

Cause of the problem: The most likely reason is that the data image made by the command is corrupted.

Now, if you have taken backup of your data, then you can restore the same from the updated backup. In the absence of a valid backup, try using Mac recovery software.

The Mac recovery software are developed with advanced techniques to recover all your deleted, corrupted or inaccessible data from a troubled hard drive. You can easily use these software without any prior knowledge as they come with detailed instructions for each step.

These huge number of hard drives have one thing in common, they store a huge amount of data, including digital data in a relatively simple manner. They are the heart and soul of the computer, and enable it to the efficient machine that a computer has become today. That is why they need to be safeguarded, otherwise, a user has to opt for hard drive recovery methods.

A hard drive is the storage area of the system and stores all programs and applications. It may have any interface, or any operating system, but nothing can prevent data loss from it when a problem comes.

These problems include, but are not limited to, corruption of file system, cross linking of files, improper shut down of the system, corruption of the master boot sector, and corruption of boot sector. In such situations the only thing that can save the work of a user is a valid and updated backup.

A backup can be taken on any device, including, tapes, USB drives, external devices, or even in the same hard drive. It is also possible to keep a backup online. A backup can be used to recover hard drive data, irrespective of the reason of data loss. But for all those who have either not maintained a backup, or have a backup, which is not valid or updated, there is still some help available.

With the advancement of technology, it has become possible to perform hard drive recovery after data loss owing to the above mentioned reasons. It is also possible to recover data that has been lost due to different reasons, including, files lost due to emptying of recycle bin or due to pressing of the ‘Delete’ button while ‘Shift’ key was pressed, data lost due to formatting or resizing of a particular drive, or due to formatting of the whole disk. There are reliable third party hard drive recovery software that are available in the market today.

Stellar Information Systems Ltd. is a pioneer in making simple, read-only, and intuitive hard drive recovery software for Windows, Novell, Mac, Linux, and Unix operating systems. With interactive graphical user interface, and a detailed user documentation, these tools are very user friendly and feature a number of options to recover hard drive data.

Scenario:

You are trying to read a particular file and the system halted with an error message leaving you to  search over any mac recovery options. The error message reads as bellow:

Error:

“-36 error (I/O Errors (bummers) ”

Probable cause:

The reason behind the above error is that the particular file is finding difficulty in either reading from the drive or writing to the drive. This is due to the fact that the file
may have been improperly written to the drive or chances are there, that the disk may be damaged. In most of the cases, the above said error indicates towards a media error or error with the hard drive.

Resolution:

Try to reboot the drive with all extensions off. Once in a while, rebooting allows you to read the data, as sometimes, the error is transient, however, this is rare.

OR

If the drive is accessible, then try copying/moving the troubled file to another disk, as it may resolve the issue.

If both the measures fail, try any mac hard drive recovery software, that only can get back your lost or inaccessible data.

These mac recovery software are capable of retrieving your lost, missing or inaccessible data from any formatted or inaccessible Mac hard drive. These commercial mac hard drive recovery utilities are designed with interactive user interface and have instructions for every step you are to make, leaving your mind absolutely stress free.

Among many available brands, Stellar Phoenix Macintosh Data Recovery 4.0 is a highly efficient tool and is immensely popular thereby. The software incorporates various attractive features, such as: Mac Style Find option, user-friendly GUI, fast scanning & searching for lost, deleted, or formatted HFS, HFS+, HFSX, HFS Wrapper and FAT volumes. This wonderful mac hard drive recovery tool is compatible with Mac OS X 10.6 Snow Leopard, 10.5 Leopard, 10.3.9 Panther, 10.4 Tiger and is undoubtedly a worthy choice.

However, there are some workarounds to deal with this problem. If these do not work, then I would recommend to use a third-party Windows hard drive recovery software to recover hard drive.

Taking a real-world example, consider that you are trying to start your Windows XP system but fail at the booting stage. An error message is displayed, that is:

“Windows could not start because of a computer disk hardware configuration problem.

Could not read from the selected boot disk. Check boot path and disk hardware.

Please check the Windows documentation about hardware disk configuration and your hardware reference manuals for additional information.”

Cause:
This booting problem can happen because of the following reasons:
The Ntoskrnl.exe file is damaged, corrupt, or missing.
There is hardware problems with the system.

In the Boot.ini file, the path of the partition is not set correctly.
Windows XP is installed at a location that is not specified in the Boot.ini file.
The boot loader section in the Boot.ini file contains invalid Default value.

Resolution:
To resolve such problems, you should perform either of the following methods to recover hard drive:
Edit the Boot.ini file: You should edit the Boot.ini file to rectify the Default value. Also, you should make sure that the all the respective entries in the [Operating System] section refer to the Boot.ini file.
Use the Bootcfg utility: You should rebuild the Boot.ini file in the Recovery Console using the Bootcfg.exe tool.
Run the CHKDSK command: You should use the chkdsk command to scan and repair any hard disk-related issues. For this, you should use the chkdsk command with the following syntax:
CHKDSK /r

These mentioned methods are sufficient enough to repair such issues. Having said that, there are times when you cannot boot the system even after using these methods. There are certain third-party hard drive recovery software that can help you to recover hard drive in such situations. These Windows hard drive recovery tools have highly interactive user interface that make the data recovery easy and safe.

Talking of such hard drive recovery software, Stellar Phoenix Windows Data Recovery is the best tool in the town that recovers data from inaccessible hard disks. Compatible with Windows 7, Vista, Server 2003, XP, and 2000, this email recovery tool recovers deleted emails from various email applications. Also, this hard drive recovery utility recovers data from FAT, exFAT, and NTFS file systems.

Consider a real-life example, in which you are unable to start your Windows XP system. Either of the following error messages is displayed:

“Invalid Boot.ini” or

“Windows could not start because the following file is missing or corrupt:

Windows\System32\Hal.dll”

Cause:

Such behavior at startup are experienced when the Boot.ini file is either missing, corrupt, or has improper entries.

Resolution:

To overcome such startup problem, you should try to create a fresh instance of the Boot.ini file. To do this, please execute the following steps:

• Modify the BIOS settings to boot the system with a CD-ROM.
• Place the Windows XP CD in the CD-ROM drive and, then restart the computer.
• Press any key to boot the system with the CD when the ‘Press any key to boot from CD’ screen is displayed.
• Enter the Recovery Console by pressing the R key.
• Enter bootcfg/list in the command prompt and press the Enter key. The existing Boot.ini settings will be displayed.
• Now, enter bootcfg /rebuild and press the Enter key to scan hard disk and rebuild the Boot.ini file.
• Then, perform the instructions as they are displayed on the screen.
• Enter Exit to restart the system. The system should start without any problems now.

There have been some cases when such resolution does not fully rectify the issue. So, you would not be able to start the computer thereby making all the valuable data inaccessible. Therefore, to recover all such data you should employ the services of a third-party Windows hard drive recovery software. Some of these tools are equipped with a Boot CD, which is very useful when the system is unable to start, like in this case.

One such hard drive recovery software is Stellar Phoenix Windows Data Recovery, which recovers lost, deleted, or formatted data even from inaccessible hard drives. Specially designed for FAT, NTFS, and exFAT file systems, this hard drive recovery utility is able to restore a huge variety of distinct file types. Well equipped to perform email recovery from MS Outlook and Outlook Express, this Windows hard drive recovery software is compatible with Windows 7, Vista, Server 2003, XP, and 2000.

Scenario:

As like every other day, when you started your Mac computer, the booting process halted and your hard disk became completely inaccessible thereof. Your head started drilling as from last 3 weeks you have not backed up your data. Now, everything lies on a trusted Mac Recovery software to get back your important data.

Error:

The Sad Mac icon appears during start up and booting process halts.

Probable cause:

Either the disk’s device driver software is damaged, or a more serious problem lies with your hard drive.
Resolution:

Use the System Installer CD and try to locate the hard disk.

If you are unable to locate the hard disk on the desktop, RAM parameters must be reset to its factory defaults, so that the computer can locate the Startup Disk.

Keep pressing the ‘P’ and ‘R’ keys during start up. Your Mac system must chime at least twice before you release the keys.

If the above measure fails, may be your device driver software is damaged. Try to rewrite/update the driver with the software that was used to format the hard disk.

Completely remove the security programs such as DiskLock, Empower, or FolderBolt before updating/installing a new driver.

If you have an Apple hard disk, use the Drive Setup program on the System Installer CD-ROM. Other than Apple disk, try the software that came with your hard disk or any third-party formatter.

If all the above fails, then only formatting and fresh installation will resolve the issues. In this case, to get back your lost data, you have to take the help of any effective Mac hard drive recovery software.

If no other option lies to resolve the issue, you have to do the formating of your drive and it will surely erase all your data in the hard disk. However, after formatting the drive or before doing so, it can be advisable to try an available Mac recovery software, that can recover back your inaccessible or lost data. These Mac hard drive recovery tools are easy to use and are cost effective with respect to the fact that these can recover back the valuable data.

Stellar Phoenix Macintosh Data Recovery is an efficient Mac recovery software that comes with high-end recovery techniques. The software is capable of retrieving your precious data from any troubled Mac hard drive. It can recover all most all types of deleted files or volumes including PTF, AAC, MXF, MUS, NSF, PMD, SHW, PS, VMX, EPS, ENC, fh3, fh5, fh7, fh8, fh9, fh10, fh11, and plist. It supports Mac OS X 10.6 Snow Leopard, 10.5 Leopard, 10.4 Tiger, and 10.3.9 Panther.

Scenario:

You tried to connect an external hard drive to your Mac computer. The drive is not recognized by the system and you receive the drive inaccessibility error message. The Error message reads like:

“Directory cannot be rebuilt, the file system is unsupported.
This disk is not a Macintosh disk.
This disk does not appear on the desktop.
This disk is <disk size> in size
Drive Format: FDisk Partition Scheme
File System: Windows/PC”

Explanation:

In this case, the drive does not show in the Disk Utility leaving the data in the external hard drive completely inaccessible.

Causes behind the issue:

Above unusual behavior by the Mac OS can be due to the corruption to the file system of the external hard drive. The corruption may have taken place due to virus attack, unexpected system shutdown, disconnecting hard drive without stopping current process or power outages.

Resolution:

• Try to repair the drive with disk utility.

While using disk utility, you might encounter the following error messages:

“Disk Utility stopped repairing drive1” because the following error was encountered:
The underlying task reported failure on exit”

Failure of the disk utility leaves you with no other other option rather than any good Mac HDD Recovery tool. These applications use powerful scanning mechanisms to scan the damaged hard drive and extract all most all the lost or inaccessible data. The good thing about these recovery softwares is that they do not require any prior knowledge or technical expertise.

Stellar Phoenix Macintosh Data Recovery is one of the leading products in the field of Mac Recovery. This is an excellent software that can successfully recover most of the file categories including application files, media files and library files. It supports recovery from HFS/HFS+/HFSX/HFS Wrapper/Fat file system volumes of Mac OS X10.5/10.4/10.3.9 and a really worthy choice in case of Mac Hard Drive Recovery.

Sometimes, the mount command does not work and thus the drive can not be accessed. The cause may be the corruption to the Linux file system and It results in critical data loss. To fix up these issues, power packed Linux hard drive recovery are the only answer.

‘fsck’ command is used to check the consistency of a file. Trying ‘fsck’ command after failing to mount, you may receive an error message.

The Error message may read like the following:

“[/dev/mapper]fsck -a /dev/mapper/mpath0p1
fsck 1.35 (28-Feb-2004)
ext2fs_check_if_mount: Input/output error while determining whether /dev/mapper/mpath0p1 is mounted.”

OR

“fsck.ext2: Bad magic number in super-block while trying to open /dev/mapper/mpath0p1
/dev/mapper/mpath0p1:
The superblock could not be read or does not describe a correct ext2
file system. If the device is valid and it really contains an ext2
file system (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
e2fsck -b 8193 <device>”

Explanation:

When you try to resolve a file system corruption problem and mount the hard drive while  using fsck command, you may get the error message indicating that the file system is inconsistent. Such circumstances lead to the failure of LINUX recovery using fsck command, and your data will remain inaccessible.

Resolution:

Boot the system in single user mode and Unmount the drives.

Check for the presence of file system, if not, apply fsck on raw drive.

If the above fails, only through LINUX hard drive recovery software, your data can be brought back. These applications incorporate high-end scanning techniques to ensure safe and successful recovery. With a friendly user interface, these tools are a boon to users who don’t have prior technical knowledge on the same.

Stellar Phoenix Linux Data Recovery is one of the robust as yet easy to use LINUX data recovery tools. This efficient software supports recovery from all Ext4, Ext3, Ext2 and ReiserFS file system volumes and is compatible with most of the popular flavors of LINUX available in the market.

Since the system files are damaged, they can not even be accessed by the regular users. This causes grave data loss situation and calls for Linux recovery, if the backup is not updated.

As a practical example of this problem, you may encounter the below error message every time you try to change the ownership of mounted hard drive on Debian Linux operating system based computer:

“debian:/# 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
debian:/# chmod -v 777 /mnt/hdc1
mode of `/mnt/hdc1′ changed to 0777 (rwxrwxrwx)
debian:/# ls -l /mnt/
total 16
drwxr-xr-x 4 root root 16384 1969-12-31 17:00 hdc1
debian:/#”

The “Operation not permitted” error may also occur if you try to mount a Linux hard drive volume, access data from a volume, move data from a location to another, or change the active partition.

Root of the problem:

This behavior may occur due to any of the below reasons and put you in need of Linux hard drive recovery alternatives:

One or more attribute bits of the directory or file are set incorrectly. It prevents you from changing disk permissions using the chmod command.

The root directory, which is repository of all sub-directories and stored data, is damaged. Thus operating system is unable to read structure of the disk.

System data structures, like file system, superblock, and iNode are either missing or corrupt. These reasons are responsible for making your Linux hard drive unusable.

Resolution:

To fix this problem, you need to repair or replace the corrupted data structures with new ones. It is possible by formatting the hard drive and reinstalling the operating system. But, this process eventually removes all your data from hard drive and causes further data loss.

In such cases, Linux hdd recovery software come to your rescue. They are advanced commercial utilities, which thoroughly scan your hard drive using high-end scanning methods and retrieve all lost data. The Linux recovery tools are easy and safe to use.

Stellar Phoenix Linux Data Recovery software successfully recovers lost, missing, inaccessible, and deleted data from Linux hard drive. The software salvages data from Ext4, Ext3, Ext2, FAT32, FAT16, and FAT12 file system volumes of all major Linux distributions like SUSE, Debian, Red Hat, and Mandriva.

In these systems, you have the option to switch to the particular system at the startup. However, sometimes due to various reasons the system is unable to start. In such situations, you should resort to performing in-place methods to fix the problem. If you are not able to address the situation, then you should use a third-party Linux recovery software to resolve the issue.

Consider a scenario wherein you have converted your system in a dual-boot system with Windows XP and RedHat Linux distribution. While in the Windows system, you accidentally clicked the ‘Hibernate’ option instead of the ‘Shut Down’ option. Now, when you start your system you are unable to do so.

Cause:

The root cause of this problematic situation is that when you chose to hibernate rather than shut down, then the MBR may have got overwritten by the GRUB. Therefore, you are unable to start the Linux system.

Resolution:

To resolve this issue, you need to restore the GRUB. To do this, you need to perform the following steps:

• Boot the system with the Fedora (RedHat) distribution CD.
• At the boot prompt, enter the following command and press Enter.
• boot: linux rescue
• You will prompted for few questions. Answer them and the Fedora installer will mount the system in the /mnt/sysimage directory.
• Make the directory as your root directory by using the following command:

# chroot /mnt/sysimage

# _

• From here, use the following command to install GRUB loader on the MBR:

# grub-install /dev/hda

• Restart the system. It should be able to boot properly now.

However, if the problem is still not resolved then you should use reformat the hard disk and reinstall the operating system. But this method would remove all the valuable data, in all probability. So to restore the inaccessible data, you should use a third-party Linux hard drive recovery software. Such Linux recovery tools are read-only in nature that use fast yet sophisticated scanning algorithms.

Stellar Phoenix Linux Data Recovery is a Linux hard drive recovery software that recovers lost, deleted, or formatted data from inaccessible Linux hard drives. It is able to recover data from various file systems such as ext2, ext3, ext4, FAT32, FAT16, and FAT12. In addition, this Linux recovery tool is capable of recovering data from various types of hard drives such as SCSI, SATA, EIDE, and IDE. Also, this Linux recovery software is supported by various Linux distributions such as Red Hat, SUSE, Debian, Caldera, Mandrake, Sorcerer, TurboLinux, Slackware, Gentoo, etc. It is compatible with Windows 7, Vista, Server 2003, XP, and 2000.