Master Boot Block
Master Directory Block (MDB), sometimes also known as Volume Information Block, hold the information about all the volumes. This information is written in the MDB when the volume is initialized. Subsequently, whenever the volume is mounted, file manager examine the information in the MDB and copies some required information into the VCB (volume control block). VCB is a private DS maintained by the file manager in computer memory.
Volume Header
Each HFS volume has a volume header of 1024 bytes in the beginning of the volume. It is located on the sector 2 of a Mac volume. It is equivalent to the MDB. The Volume Header stores a wide range of data about the volume itself, for instance the size of allocation blocks on the drive, a timestamp the shows when the volume is formed and some other volume structures like Extent overflow file or Catalog File. Volume Header is located always in the same place.
MDB and Volume Header are the most important data structure of any volume in Mac OS X operating system as they hold complete information related to files, volumes and also hold catalog file. Catalog file is most important file that helps operating system to find and access the particular file requested by the user. If any kind of problem occurs with Master Directory Block or Volume header, it may cause serious problem of data loss. Corruption and damage are problems that most probably happen with MDB and Volume Header.
Master Directory Block and Volume Header Corruption are the most common reasons of data loss in Mac operating system. If these get corrupted, operating system fails to find and display the files. There are several reasons of MDB and Volume Header corruption. Some common reasons are:
Human error
Partition table corruption
Partition sectors damaged in disk
Catalog file corruption
Catalog file’s node corruption
Internal file system error
Extent files damaged
Virus infection
Unexpected system failure
If any of these situations occurs, it may corrupt Master Directory Block and Volume Header. In this situation, general user commonly can not identify that what is the real problem and what solution I should use. You should always keep in mind that whenever your system display an error message “file *.* not found”, your MDB and Volume Header have corrupted. This is the worst scenario of data loss. In these conditions you need to recovery your data and Mac data recovery software can help you to overcome this problem.
data recovery mac software is the software that can recover data from damaged or corrupted MDB and Volume Header of Mac OS X volumes. Mac Data Recovery software use advanced algorithms to search and located the lost data in Mac operating system. These software display the search results in easy to access and find tree format. You can select the required data from this search result and can save them to specified location.
