CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [184]
Note that under normal circumstances, Windows does not actually delete files when you press the DELETE key. Instead, Windows moves the files to a special hidden directory that you can access via the Recycle Bin. The files themselves are not actually deleted until you empty the Recycle Bin. (You can skip the Recycle Bin entirely if you wish, by highlighting a file and then holding down the SHIFT key when you press DELETE).
Because all of the data for MOM.TXT is intact, you could use some program to change the σ back into another letter and thus get the document back. A number of third-party undelete tools are available. Figure 12-17 shows one such program at work. Just remember that if you want to use an undelete tool, you must use it quickly. The space allocated to your deleted file may soon be overwritten by a new file.
Figure 12-15 Three files saved
Figure 12-16 MOM.TXT erased
Let’s say you just emptied your Recycle Bin. You now save one more file, TAXREC. XLS, a big spreadsheet that will take six clusters, into the same folder that once held MOM.TXT. As Windows writes the file to the drive, it overwrites the space that MOM.TXT used, but it needs three more clusters. The next three available clusters are 3AC4, 3AC5, and 3AC6 (see Figure 12-18).
Figure 12-17 WinUndelete in action
Figure 12-18 TAXREC.XLS fragmented
Notice that TAXREC.XLS is in two pieces, thus fragmented. Fragmentation takes place all of the time on FAT16 systems. Although the system easily negotiates a tiny fragmented file split into only two parts, excess fragmentation slows down the system during hard drive reads and writes. This example is fragmented into two pieces; in the real world, a file might fragment into hundreds of pieces, forcing the read/write heads to travel all over the hard drive to retrieve a single file. You can dramatically improve the speed at which the hard drive reads and writes files by eliminating this fragmentation.
Every version of Windows comes with a program called Disk Defragmenter, which can rearrange the files into neat contiguous chunks (see Figure 12-19). Defragmentation is crucial for ensuring the top performance of a hard drive. The “Maintaining and Troubleshooting Hard Drives” section of this chapter gives the details on working with the various Disk Defragmenters in Windows.
Figure 12-19 Windows Disk Defragmenter
FAT32
When Microsoft introduced Windows 95 OSR2 (OEM Service Release 2), it also unveiled a totally new file format called FAT32 that brought a couple of dramatic improvements. First, FAT32 supports partitions up to 2 terabytes (more than 2 trillion bytes). Second, as its name implies, FAT32 uses 32 bits to describe each cluster, which means clusters can drop to more reasonable sizes. FAT32’s use of so many FAT entries gives it the power to use small clusters, making the old “keep your partitions small” rule obsolete. A 2-GB volume using FAT16 would use 32-KB clusters, while the same 2-GB volume using FAT32 would use 4-KB clusters. You get far more efficient use of disk space with FAT32, without the need to make multiple small partitions. FAT32 partitions still need defragmentation, however, just as often as FAT16 partitions.
Table 12-2 shows cluster sizes for FAT32 partitions.
Table 12-2 FAT32 Cluster Sizes
Essentials/Practical Application
NTFS
The Windows format of choice these days is the New Technology File System (NTFS). NTFS came out a long time ago with the first version of Windows NT, thus the name. Over the years, NTFS has undergone a number of improvements. The version used in Windows 2000 is NTFS 3.0; the version used in Windows XP and Vista is called NTFS 3.1, although you’ll see it