Defective data block
As a defective data block (Engl. Bad Block ) is called in storage media such as hard disks , floppy disks or flash memories an unusable, d. H. Data block that can no longer be used for write and read operations.
Defective data blocks occur due to manufacturing errors, but can also arise during runtime due to signs of wear and tear. Incorrect write operations can also result in data blocks being marked as defective. Just in case, there is software that can remove the mark again. If defective data blocks occur in a memory, this does not necessarily mean its complete failure. A software component in the hard disk firmware or in the flash driver can automatically replace the defective memory blocks with error-free memory blocks from a reserve area using an allocation table. This process is known as remapping and a as bad block management (Engl. Block Management System Bad ) known software component performed.
The assignment of logical to the actual, physical memory blocks carried out during remapping enables transparent access to the data blocks of a memory - without having to take into account its physical defects. As long as the reserve area is not exhausted, the memory can continue to be used without restrictions.
If defective data blocks accumulate conspicuously on hard drives, a more serious mechanical surface defect - usually caused by a head crash - can be expected. To avoid data loss, the hard drive in question should be replaced as soon as possible.
The clipping level is a measure of security against surface defects and thus against write and read errors on floppy disks .
