Optimizing Disks CGS2564

Disk Directory What files are on the disk

File Allocation Table Where files are located

File Allocation Table Files deleted and reduced in size

Disk Directory File increases in size

File Allocation Table File increases in size

File Allocation Table File increases in size Chain of Clusters

Fragmentation A normal occurrence Over time - slow disk access Defragmentation Puts all files in contiguous clusters

Check Disk Fixes physical and logical disk problems Physical Logical Checks for bad sectors Moves data to good sectors if possible Updates FAT (don’t use this sector) Logical Corrupted FAT Lost clusters Cross linked files

Corrupted FAT Repairs table from second copy if possible

Lost Clusters FAT shows clusters in use but no entry in directory for them or Directory lists file but no (or incomplete) entries in FAT Lost Clusters

Lost Clusters Causes Symptoms Power failure (especially during disk access) Not closing files and exiting programs properly Not shutting down Windows properly Symptoms Can’t open file Frequent system lockups Especially during disk access Other “strange” problems

Lost Clusters Check Disk What to do with them? Converts lost clusters to files What to do with them? Examine in editor Determine if they contain recoverable data Open in application and salvage what you can Otherwise delete Run applications and reinstall if necessary

Check Disk Disk with corrupted file

Check Disk Recovered files stored in FOUND folder

Check Disk Recovered file examined for clues to its content