A hard disk cluster or the allocation unit is the group of sectors and indeed the smallest unit to hold a file. The size of a cluster depends upon the size of the volume or drive and is meant to enhance the storage efficiency. All Windows file systems, such as FAT, exFAT, NTFS, NTFS5 etc. use a definite cluster size to manage the data in the hard drive and the partitions are defined in terms of clusters at the time of formatting of the disk.
Still, there are several third-party tools available in the market to safely modify the existing cluster size. But, it is always advisable to take backup of your important data prior to the usage of such utilities as the process may cause serious corruption to the file system and data loss or inaccessibility. However, if you still witness any instance of data loss, you can use hard drive recovery software to recover back your valuable data.
In order to describe the above situation, let us suppose that you used a third-party software to modify your hard drive cluster size. The process got completed lucidly until the next time, you tried to boot the system. The next time, when you boot your system, the booting process halted in the middle and you tend to receive an error message. Thereafter, all your data stored in the hard drive became inaccessible. The error message can be read as below:
“A Disk read error occurred. Press Ctrl-Alt-Del to restart”
The above error message appears because of a possible corruption to the Master Boot Record or MBR.
Note: MBR is the boot sector or the first sector of a partitioned storage media. Moreover, MBR is responsible for recognizing the partitions and loading of the operating system.
In order to resolve the above error, you need to boot your system with the Windows installation CD or DVD. Thereafter, at the command prompt, run the command 'fixmbr to repair the MBR.
However, if 'fixmbr' command fails to repair the MBR, you have to reformat the hard disk and make a fresh installation of the operating system. Formatting erases the whole data from the hard drive and you have to restore the data from the backup. In case, backup is not available or failed to restore back the data, only any Windows hard drive recovery software can help you recover your data.
Stellar Phoenix Windows Data Recovery is a highly appreciated utility to recover hard drive data irrespective of the data loss situations. The software is compatible with Windows 7, XP, Vista, 2000, 2003 and is capable of recovering any deleted, lost, formatted or inaccessible data from FAT and NTFS file system based drives.
HDD recovery in case of -A Disk read error