Shulou(Shulou.com)11/24 Report--

The editor would like to ask, when we operate a personal computer, what should we do if we find that the data is lost? Can the lost data be recovered and how? What should be paid attention to during the recovery process?

The following answers will be revealed one by one.

01. Why are there no good data? It is usually due to a hard disk failure, which is mainly divided into two categories:

Logic failure (software available to fix it)

Including: erroneous deletion, mispartitioning, miscloning, misformatting and other manual sliding operations, or sudden power outage, malicious deletion of viruses and other abnormal situations.

Physical failure (equipment maintenance required)

Mechanical hard disk may have hard disk circuit board or disk body failure, such as head or track damage, disk scratches.

Solid-state hard drives may have circuit or component failures, such as main control damage and flash memory particle wear.

02. Can the lost data be recovered? The editor can only answer: not necessarily. Only when we know the cause of data loss first, can we prescribe the right medicine and improve the data recovery rate as much as possible.

When a physical failure occurs on a mechanical hard disk:

■ usually requires professionals to open the hard drive and replace faulty parts in a dust-free environment.

■ if the hard disk is seriously damaged, it is theoretically possible to use magnetic tunneling microscope to find data blocks on the disk.

When a physical failure occurs on a solid state disk:

The damage probability of ■ master chip is the highest, and the firmware development level and read and write control algorithms adopted by different manufacturers are different, so it is difficult to recover data.

If the ■ is damaged by flash memory particles as a data storage carrier, it can basically give up recovery.

As the recovery principles and techniques involved in physical faults are relatively complex, they will no longer be introduced.

In short, please remember: if it is a physical failure that leads to data loss, quickly find a professional organization to solve, there is still a chance!

Let's focus on the problem of data recovery for logic failures: in fact, there is still hope for mechanical hard drives, but there is little hope for solid-state drives.

Why do you say that? Let's start with the principle of data recovery.

03. What is the principle of data recovery? (1) what you delete is not the data, but. Everyone is familiar with the following situation:

When deleting a file, usually right-click the file and select Delete, and find that the erroneous deletion can also restore the file in the Recycle Bin. Only by emptying the Recycle Bin will the deleted file disappear.

But the editor wants to tell you: in fact, even if you empty the Recycle Bin, the deleted files remain on the hard drive, but you can no longer call / open it.

This is because:

When storing files, the system will pull out a small book to record key information such as the attributes and location of each file, and the data will be stored on the hard disk in binary form.

When a file is called, the hard disk has to consult the record to know which binary data stored in which combination is the corresponding file.

When a file is deleted, the system will make a delete mark on the page where the file is recorded in the notebook, indicating that the record is invalid and the storage space is available, but the data will not be erased directly from the hard drive.

The binary data on the hard disk is so vast that once the file is deleted to invalidate its record, it is equivalent to that the data is lost in the sea and then scattered everywhere. If there is no location, it can not be salvaged, even if it exists, it can not be seen or used.

Therefore, it is not the data that is deleted, but the way the data is located and invoked.

(2) the data recovery principle of the mechanical hard disk is in the mechanical hard disk, the record is invalid after deleting a file, and its storage space can be occupied by the new file by default, and the new data can be overwritten.

It is important to note that once the new data completely covers the old data, the old data may really disappear!

The principle of data recovery of mechanical hard disk is coming out: under the premise that the space occupied by deleted files is not covered by new files, cancel the mark of deleted files and restore file records.

In addition, operations such as reading, writing, deleting and modifying the file may cause the changed data to be scattered in the available space, form file fragments, and increase the seek time of the mechanical hard disk.

File fragments not only affect the performance of mechanical hard drives, but also increase the risk of data corruption and loss. Therefore, if the deleted file is fragmented, it may affect the success rate of data recovery.

(3) the principle of data recovery of solid-state disk is different from that of mechanical hard disk. Solid-state disk does not support overwriting. The deleted data must be completely erased to make room before new data can be written. If you erase and then write for a long time, it will cause the hard drive to slow down.

In order to improve performance, the TRIM instruction arises at the historic moment: after the file is deleted, when the solid state disk is idle for reading and writing, the old data is erased in advance, so that more free space is available, and new data can be written at any time without waiting.

Therefore, in order to recover the data on the solid state drive, you must unmark the file deletion and restore the file record before TRIM erases the data.

Of course, this principle is only based on theory, because we can not grasp the actual erase speed, and it is even more difficult to recover after erasing the data.

04. What should I do when I find that the data is missing? Friends have learned the theoretical knowledge, but how to deal with the situation of data loss?

STEP 1 stop operations stop reading, writing or cleaning operations in progress as soon as data loss is found, to prevent writing new data from overwriting or defragmenting causing missing data to be cleaned up.

STEP 2 Analysis if the fault ■ is a physical failure, or if the data loss occurs on the solid state disk on which the TRIM has been executed, it is difficult to recover, so it is recommended to contact a professional organization to deal with it.

If the ■ is mistakenly deleted, misformatted and other logic failures, bold friends can try to use a variety of free / paid software on the Internet to restore. If it is extremely important to lose data, consult a professional organization as soon as possible.

STEP 3 backup data back up the hard disk data as soon as possible (such as using the hard disk cloning tool) to retain the marked deleted data as completely as possible.

In this way, you can try various recovery methods later, with backup in hand, so you don't have to worry about accidental damage to the data during the recovery.

It is important to note when STEP 4 attempts to resume the use of data recovery software:

■ is best to use other computers to download software to a removable hard drive or USB drive, and then connect to run the software on a computer that has lost data.

The data recovered by ■ cannot be saved to the original hard disk, so data overwriting must be avoided.

■ can use a variety of data recovery software, so that the aggregated recovery data may be more complete.

The recovery of data is only to mend, what we should do is to take precautions and maintain the security of the data.

How to maintain data security? STEP 1 provides a safe environment ■ has the conditions to do a good job of computer heat dissipation, to avoid high temperature leading to hard disk failure.

■ shuts down normally to avoid sudden power outage and no power for a long time to affect the hard disk work.

■ regularly upgrades the computer protection system and updates the hard disk firmware.

STEP 2 to avoid data leakage, "water can carry the boat, can also overturn the boat" truth everyone knows ~ how to completely delete private data and can not be restored?

■ usually uses the file shredding feature, which works by repeatedly writing random data to the location of the deleted data and overwriting it multiple times.

■ can perform miracles and smash the hard drive if it is not assured.

STEP 3 rational use of hard disk ■ do not store important files on the system disk or desktop, which not only affects the running speed of the computer, but also difficult to recover once lost.

■ systems and software can be installed on solid-state drives to improve speed, and files can be stored in large-capacity mechanical hard drives.

■ mechanical hard disk defragmenting files regularly can not only read and write data more smoothly, but also improve the success rate of data recovery.

Solid state drives store data based on flash memory, seek time is constant, and limit the number of reads and writes, defragmentation will affect the life of the hard drive. )

STEP 4 do a good data backup no matter using mechanical hard disk or solid state hard disk, the most important thing is to do a good data backup!

■ can deploy NAS, a network data store that supports sharing, if the budget is adequate.

If the budget of ■ is small, you can use removable hard disk, network disk, or build RAID 1 (two hard drives are mirrored and backed up synchronously).

06. To sum up, my friends have gained new knowledge today:

■ data loss is usually due to physical or logical failure of the hard disk.

The principle of data recovery of ■ mechanical hard disk and solid state hard disk under logic failure.

4 steps to deal with when ■ discovers that data is missing.

Four suggestions for ■ to maintain data security.

Finally, the editor wants to say:

The data is valuable, and the loss price is even higher.

There is a way to restore, backup is the most reassuring.

I hope everyone will not encounter the situation of data loss and need to be recovered. We should pay attention to the data security at ordinary times.

This article comes from the official account of Wechat: ZTE document (ID:ztedoc), author: ZTE document

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