3.six Really hard disk defect

1. Classification of defects

If it's located that a certain tough disk can't function ordinarily, it is actually known as a 'defective tough disk' (DefectHardDiSk).

According to the maintenance experience, the defects in the difficult disk are divided in to the following six categories:

①Bad sectors, also called defective sectors;

② Track servo defect;

③ Defect of magnetic head assembly;

④The program data is disordered;

⑤ Defects in electronic circuits;

⑥ Complete performance defects.

( data recovery software free download ) Terrible sectors.

A undesirable sector refers to a sector that cannot be accessed typically or can't be study or written correctly. The basic performance is: 'bad clusters' are located right after advanced formatting; 'B' mark is located with tools like SCANDISK; or 'sector error prompt' is found with some detection tools.

Frequently, each sector can record 512B of information. If any one of the bytes is abnormal, the sector is often a defective sector. Additionally to recording 512B of data, each and every sector also records some details, for example flag data, check code, address details, and so on., any element with the info is just not regular will cause defects within the sector.

Most experienced inspection software finds comparable error messages when they find defects throughout the inspection method. Prevalent sector defects mainly include things like the following situations.

① Check error (ECCuncorrectableerrors), also known as ECC error. Every time the technique writes data towards the sector, it generates a verify code depending on these information right after a certain algorithm operation, and records this verify code inside the info region of ​​the sector. Later, when reading information from this sector, the calibration code might be study in the identical time, and the data will be recalculated to check whether the result is constant using the calibration code. If they're consistent, the sector is regarded normal along with the stored data is appropriate and valid; if they're inconsistent, the sector is regarded to be in error, which can be a verification error. That is the key type of defect in really hard drives. The primary causes of this defect consist of harm towards the magnetic media on the surface in the disk, abnormal writing on the really hard disk, and variations within the algorithm from the check code.

②IDNF error (sectorIDNotfound), that's, the sector mark is incorrect, causing the program to seek out the corresponding sector when it must read and write. The bring about of this error could possibly be that the program parameters are disordered, resulting in disordered internal address translation, along with the method cannot find the designated sector; or it might be that the flag details recorded in a sector is incorrect as well as the program can't properly identify the sector.

③AMNF error (AddressMarkNotFound), that's, the address facts is wrong. Commonly, as a result of an error inside the address details recorded inside a sector, when the technique accesses it, it finds that the address info is inconsistent using the details arranged by the system.

④ Undesirable blockmark (Badblockmark). Some software or virus programs can forcibly write terrible block marks on some sectors, so that the system will not use these sectors. Strictly speaking, this predicament will not be necessarily a defect with the tough disk itself, nevertheless it just isn't uncomplicated to get rid of these poor block marks.

(two) Track servo defect. The majority of the present difficult disks use embedded servos. Each and every normal physical track in the difficult disk is embedded with 1 or several pieces of data as servo info, in order that the magnetic head can accurately locate and identify the right quantity of physical tracks when in search of. When the servo facts of a physical track is damaged, the physical track may not be accessible. Track servo defects typically manifest as an abnormal interruption from the partitioning procedure; the formatting procedure can't be completed; when it truly is detected with a detection tool, it exits or freezes halfway, and so on.

(3) Defects within the magnetic head assembly. Refers to a circumstance exactly where a part in the magnetic head assembly in the tough disk is abnormal, causing some or all the physical heads to become unable to study and create ordinarily. Including head put on, head contact surface is dirty, head swing arm deformation, voice coil harm, magnetic specific displacement, etc. The general overall performance is: just after the power is turned on, the sound of your head movement is obviously abnormal, and the really hard disk can't be detected by the technique BIOS; the partition can't be formatted: right after formatting, a large number of poor clusters are distributed from front to back, and so on.

(4) Method information is disordered. Every difficult disk has a technique reserved region (ServiceArea), which is divided into numerous modules to retailer numerous parameters and applications. When the tough disk is powered on for self-test, the majority of the programs and parameters must be named. If these programs and parameter modules could be study out, and the verification is typical, the hard disk enters the preparation state. If some modules can't be read or the verification is abnormal, the really hard disk can not enter the preparation state. Generally, the BIOS in the Computer system can't detect the tough disk, or it can not study or write towards the challenging disk. For example, the popular challenges of some series of hard disks: the head on the American Diamond Series two really hard disk is powered on along with the motor stops. Just after the Fujitsu MPG series is powered on, the head typically seeks, but the BIOS cannot detect it.

(five) Defects in electronic circuits. Refers towards the open circuit or short circuit of some circuits in the electronic circuit board from the tough disk, and some electrical elements or IC chips are broken. Some parts might be identified by observing the circuit board, and a few components can only be confirmed by measuring with all the instrument. Commonly, the difficult disk can not begin commonly soon after power-on, or the head seek is abnormal after starting, and so on.

(six) Comprehensive functionality defects. website have some chip qualities changed for the duration of use: or some tough thieves: slight adjustments in physical structure just after vibration (for example damage to the motor spindle); or some difficult disks have style defects ... ultimately resulting in poor difficult disk stability, or element The functionality doesn't meet the normal requirements. 1 manifestation is: the noise increases drastically in the course of operate: the reading and writing speed is of course as well slow: a big variety of equivalent failures occur in the difficult drives of your similar series; sometimes there is no such failure, and so on.

2. How manufacturers deal with defects

The following describes some fundamental processing procedures of your hard disk factory.

(1) The hardware aspect on the challenging disk is assembled on the production line, and also the servo signal (Servowrite) is written towards the disk with specific gear.

( https://toothstamp69.bravejournal.net/post/2020/06/06/360-security-guards-reinstall-the-technique:-1.-Open-360-safety-guards-and-download-system-reinstallation-;-two.-Pick-the-kind-of-reinstallation,-you-could-pick-out-a-pure-technique,-but-you-should-back-up-important-points-ahead-of-time;-3.-In- ) Format the system reserved region (serviceareg) from the really hard disk, and write the program module and parameter module for the method reserved region. The program reserved region is generally positioned in the first dozens of physical tracks on the physical surface of difficult disk 0. The written plan modules are normally applied for internal tough disk management, for example low-level formatting procedures, encryption and decryption procedures, self-monitoring procedures, and automatic repair procedures. The written parameters include things like model quantity, serial quantity, capacity, password, manufacturer and production date, region allocation table, defect table, error record, usage time record, S.M.A.R.T table, and so forth. The information volume ranges from a number of hundred KB to several MB. Occasionally the parameters do not change once written, such as model, serial number, production time, and so on .: even though some parameters is often automatically modified by internal management procedures in the course of use, including error records, use time records, S.M.A.R.T records, etc.

(three) Comprehensively scan all used disc surfaces in line with physical addresses, verify out all defective tracks and defective sectors, and record these defective tracks and defective sectors within the permanent defect list (P-list; Permanentdefectlitst). This scanning approach is very strict and may verify out unstable and unreliable tracks and sectors, and treat them as defects. The density of present challenging disks is particularly high, and it is actually difficult to totally keep away from defective tracks or defective sectors even though the production procedure from the disk is so precise. Typically, you will discover dozens and even tens of a huge number of defect records in the P-List of new hard disks. P-list is reserved inside the reserved location of ​​the system, along with the general user cannot view or modify it.

Throughout the low-level formatting process, all tracks and sectors are numbered, information and facts is rewritten, and zero elimination is performed. When numbering, the skipped approach is used to ignore the trapped tracks and defective sectors recorded within the P-list, to make sure that these defective tracks and defective sectors will not and cannot be made use of within the future. As a result, new challenging drives cannot be detected for defects when they are sold.

three. Tracks and sectors around the disk

A track is a single data storage circle on a single side of a disk. If the track is made use of as a storage unit, it really is as well low from the perspective of information management efficiency. As a result, the track is divided into quite a few numbered areas, referred to as sectors. These sectors represent the segmentation of tracks. Inside the Pc method, the sector capacity generated by the typical formatted program is 512B. Note the relationship amongst 'sector' and 'cluster'. 'Cluster' is the smallest disk unit that the operating technique can manage when reading or writing a file. A cluster is equal to a single or far more sectors.