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Popular Science: Data Protection and Mechanical Hard Drive Recovery


What is likelihood that you will experience such a hard drive failure?

Popular Science: Data Protection and Mechanical Hard Drive Recovery

"You can't forcibly unplug your hard drive and force shutdown your computer" is first piece of knowledge that many people learn when learning computers when they're young.

According to ordinary people, result of forcibly turning off power is often loss of data on hard drive or damage to entire hard drive.

So, will a forced power down actually cause data loss on hard drive? It's really possible.

When talking about protecting a hard disk from power outage, we should look at it from two sides, because now we are talking about two types of hard disks, one of which is mechanical hard disks, which are usually used for large capacity requirements and low-performance storage , and other is Solid State Hard Drive is generally rarely used as a storage drive due to its high price.

Let's start with a mechanical hard drive. Damage to a mechanical hard drive when power is turned off should start with its principle.

In 1973, IBM successfully developed a new type of hard drive, IBM334. This hard drive has several coaxial metal platters coated with a magnetic material. They are sealed in a box with a moving magnetic head that can read changing magnetic signal from a spinning disk - this is ancestor of hard disk we use today, and IBM calls it hard drive.

At present, with exception of SSD, which is commonly known as a solid state drive, most of storage devices on market are based on Winchester mechanical hard disk structure. The principle of operation of a hard drive mechanical hard disk is similar to that of a phonograph in a confined space, difference is that distance between magnetic head and platter is only 10 nanometers, and a slight movement of magnetic head scratches disk. dish.

A power outage is clearly included in concept of "slight inattention". But why do you rarely experience data loss and hard drive corruption after forcibly shutting down your computer? Because after decades of research, mechanical hard drive manufacturers have already developed a relatively mature power-off protection solution.

To put it simply, a very small "battery" is installed in hard drive. When external power supply is turned off, mechanical hard drive will use power from this battery to move magnetic head to a safe location. to avoid scratching disc.

This firstly ensures that a sudden power failure does not damage or lose a large amount of data, but only a small portion of data that has not yet been written in time.

Of course, disk damage is not limited to accidental power failure. Normal aging, vibration at a distance, dropping and external damage can cause damage to internal precision components and disc discs. EIf hard disk is damaged and cannot be read, it cannot be saved. The first thing to do is to stop reading and writing to hard disk to avoid further damage to hard disk.

A professional data recovery organization must then perform a "teardown", that is, open sealed hard drive for targeted repair.

Generally speaking, repair steps are as follows:

The first step is to open hard drive in a dust-free working environment and replace damaged head or other hard drive components.

The second step is to recombine recently replaced parts with original parts to form a hard drive and debug corresponding firmware.

The third step, magnetic cloning, completely copies information from damaged hard drive to an undamaged new hard drive. This part takes most time in whole data recovery. Depending on how damaged drive is, this can take anywhere from a few hours to a month.

The fourth step is to reorder data on cloned hard drive and extract recovery data.

What is likelihood that you will experience such a hard drive failure?

According to a 2013 report by online backup service provider Backblaze, out of 25,000 mechanical hard drives purchased, 5.1% of hard drives will fail within 18 months and 1.4% of hard drives will fail within 18 months. The failure occurs within about 36 months, failure rate rises to 11.8% after 3 years, and probability that hard drive is still intact after 4 years of use is about 80%.

The general average life of mechanical hard drives at time was 6 years.

To ensure "absolute security" of data, critical application scenarios such as security often use disk arrays - multiple hard drives store same data at same time - which can greatly improve data security.

Of course, most important thing is to take care of your hard drive like a child and not abuse it.