Elementary knowledge of data recovery

Ⅰ.Elementary knowledge of data recovery
1.Connotation of data
Connotation of data is comprehensive, it includes not only multi-media files such as data
documents, images, voices that stored in file system or data base, but also hardware information,
network addresses and network services, which are used to deposit and manage those information.
2.The essence of data recovery
Data recovery means retrieving lost, deleted, unusable or inaccessible data that lost for various
reasons.
Data recovery not only restores lost files but also recovers corrupted data.
On the basis of different lost reason, we can adopt different data recovery methods. There are
software and hardware reasons that cause data loss, while we can recover data by software and
hardware ways.
Being different from prevention and backup, data recovery is the remedial measure. The best way
to insure the security of your data is prevention and backup regularly. To operate and use your data
according to the normative steps, you can reduce the danger of data loss to the lowest.
3.The scope of data recovery
There are so many forms and phenomenon on data problem, we can divide the objects or scope of
data recovery according to different symptoms.
System problem
The main symptom is that you cannot enter the system or the system is abnormal or computer
closes down. There are complex reasons for this, thus we need adopt different processing methods.
Reasons for this symptom may be the key file of system is lost or corrupted, there is some bad
track on hard disk, the hard disk is damaged, MBR or DBR is lost, or the CMOS setting is
incorrect and so on.
Bad track of hard disk
There are logic and physical bad track. Logic bad track is mainly caused by incorrect operation,
and it can be restored by software. While physical bad track is caused by physical damage, which
is real damage, we can restore it by changing the partition or sector. When there is physical bad
track, you’d better backup your data for fear that the data can not be used any more because of the
bad track.

Partition problem

Partition problem
If partition can not be identified and accessed, or partition is identified as unformatted, partition
recovery tools such as Partition Table Doctor can be used to recover data.
Files loss
If files are lost because of deletion, format or Ghost clone error, files restoring tools such as Data
Recovery Wizard can be used to recover data.
Password loss
If files, system password, database or account is lost, some special decryption tools that
correspond to certain data form such as Word, Winzip can be used.
Files repair
For some reasons, some files can not be accessed or used, or the contents are full of troubled
characters, the contents are changed so as they can not be read. In this condition, some special
files restoring tools can be tried to restore the files.
4.The principle of data recovery
Data recovery is a process of finding and recovering data, in which there may be some risk, for no
all situations can be anticipated or prearranged. It means maybe there will be some unexpected
things happen. So you need reduce the danger in data recovery to the lowest:
Backup all the data in your hard disk
Prevent the equipment from being damaged again
Don’t write anything to the device on which you want to recover data
Try to get detailed information on how the data lost and the losing process
Backup the data recovered in time.
Ⅱ.Data loss
Actually, there are various reasons that cause data loss; software, hardware, factitious, natural,
intended, unintended, all may cause data loss or damage on storage devices.
Generally, There are two main reasons for data problem: software and hardware whose
corresponding reasons are software reason and hardware reason.
1.Software reason
Virus, format, mis-partition, mis-clone, mis-operation, network deletion, power-cut during
operation all may be the software reasons. The symptoms are usually mis-operation, read error,
can not find or open file, report no partition, not formatted, password lost and troubled characters.
A: Computer Viruses: some malicious virus programs will destroy data, overwrite, or erase the
data contents.
B: Mis-format: fast or completely format partition, thus changing the file system form (NTFS,
FAT32) of partition.
C: Mis-Clone: when backing up the hard disk, mis-clone or overlay the original data on hard disk.
For these, we can use software tools to recover it. So called soft recovery means data can be
recovered by software, not referring to hardware fixing operation for its fault is not because of
hardware failure.
The following are prompts that system can not start up normally: