Every plane of the hard disk has the both writable sides on to a number of tracks and every track is divided on sectors. The planes are adjusted perfectly and the 0 track from plane 1 can be exactly over the 0 track of plain 2 and 3. To gain access to any track on one of the plains the arm that sustains the reading head will move to that specific track. Because this method requires only one moving part in to the hard disk simplifies the working method and there are cheaper hard disks. But it is a major disadvantage because if we want to access certain information all of the reading heads will be moved in that direction and if the hard disk is required more information per minute it will be unable to fulfill our request and then the risk of errors increase very much and the logical errors appear.
This type of errors appears on the allocation table of files and folders. The most know error that happens to every one of us (we are sure that every body has encountered the problem but they didn’t know what is it) is the information about the available space on our hard disk. We all know that in time the working status of the hard disk can create a few problems. Actually the physically space on the hard drive is divided on blocks and if a certain area is affected then the entire block become unstable. Let’s say that you are saving something on you hard disk just in the same place where a bad block is. When you write it may not give you a warning about the bad block and continue but when you will try to access the information or to copy it you will get the an error message because the head readers are understanding other information then the previous that was written on it.
The computer does not know what was previous written there but you can verifies throw a control key if the initial data that where written are debased. Practically the entire program that was installed becomes unstable.
A hard disk has thousands of blocks, so a few bad blocks don’t mean anything. But you must know that once the bad blocks appear on a hard disk their tendencies are to multiple. You can still use your hard disk for a long period of time whit the condition to identify the bad blocks, mark them, and in that way you will indicate to the hard disk to avoid that portion for the writing process. You can do the indication process by using a physically scan. This will take some time because every block is tested by writing some information on it and then red them to see the condition of the block and if the information is correctly returned. The time that you need to this operation is directly proportional whit the size of your hard disk and it is recommended to do it once a year or when reading problems appear on your hard disk.
In a conclusion the bad blocks are parts of your hard disk that can not be used anymore because that part of the platens is destroyed. The bad blocks are unfortunate parts of our hard disk that can create errors and destroys the right functionality of our programs. There are some files that will help the bad blocks to multiply such us movie files or a single file that are larger then 300 megabits. Those files are written from one sequent and if there are written over an already created bad block the entire file can not be read but also increase the chance when we try to run it, to create a bad block on the correct blocks on the platens.