DATA STORAGE RETRIEVING FILE FROM A DISK
When a user tries to open a file, the program call on its API and Window’s DLLs. Windows XP call on Installable File System (IFS) manager to pass control over to the appropriate file system driver (FSD) from one of the 4 storage systems (NRFS, VFAT, CDFS and Networks). Then the FSD get the disk location of the first cluster of the letter file from VFAT or from MFT (master file table). Finally the adapter take over, moving the read/write head to the correct series of disk cluster to retrieve he file and copied to the memory so the PC can work with it.
MIRROED DRIVE ARRAY (RAID)
As data integrity is more important than speed and there are only two hard drives, the best solution is mirrored drive array (RAID 1). Redundant array of independent drive (RAID) controller is to write every file to two or more drivers at the same time. A mirrored array can read the data twice faster as the controller reads alternate file cluster simultaneously. In case of a read failure, the controller simply reads the intact version of the file from the undamaged drive. If the damage is caused by a media defect, the controller automatically reads the data from the intact copy of the file on the other drive and writes it to a new, undamaged area on the drive where the defect occurred.
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