Solving Problems in Windows XP File System
By Cássio Lima on September 16, 2005


Introduction

Last week something strange happened to me, and I believe the same has happened to many of you. I was at my computer, writing and concentrating in my thoughts, when suddenly I moved very fast on my chair and kicked the voltage stabilizer with my right foot, turning everything off. My first reaction was to hold my head with the hands and deeply regret what I had done. After the anger was gone, I used my right foot again, this time to turn the stabilizer and the PC. When the operating system – Windows XP – was being loaded, surprise: a weird blue screen appeared with the following error message: STOP 0x000000ED UNMOUNTABLE_BOOT_VOLUME. The file system of my Windows XP had been corrupted and I was unable to use my computer.

In this tutorial we’ll talk about the operation and how to solve problems in Windows XP file system.

FAT32 vs. NTFS

Windows XP supports two kinds of file systems: FAT32 and NTFS. The FAT32 system was introduced with the Windows 95 OSR 2, while the NTFS is the native system of Windows NT, Windows 2000/2003 and Windows XP. The FAT32 system uses a file allocation table (FAT) to store the use of each cluster in a disk. In the FAT32 system the files are stored in clusters (set of sectors) and in the allocation table there is a register of which clusters are in use by each file in the disk. Each entry in the allocation table points to the next cluster that represents the file (in case the file takes more than one cluster). For example, imagine that a file called System.txt is stored in the disk in clusters 10, 11, 12, 13, 14 and 15. The first cluster of a file in the FAT system is stored in a structure called directory. The other clusters are stored in the allocation table. Thus, the directory points out “10” as initial cluster. In the allocation table, the position 10 will point out to the next cluster in the chain that represents the file, in our example, cluster 11. Position 11 will point the value 12, and so on. The last cluster in a sequence that represents a file has a special marker, called EOF (End Of File). In short, if a file is stored in more than one cluster in the FAT32 system, each cluster where the file is stored in contains a pointer to the next cluster in the chain.

As the FAT32 system, NTFS also uses a table – called MFT (Master File Table) – to register the use of each cluster in a disk. That table contains much more information about the files than the FAT table, which stores just the clusters that compose the file.

The NTFS system has characteristics that are not presents in FAT32 system and which make this system ideal for applications that demand more security and control, which is the case of network servers. Those characteristics include:

The NFTS system is much safer and stable than the FAT32 system due to the way in which it was developed, and also due to a feature called Log of Transactions. Each NTFS partition keeps a log of transactions of every change made in the disk. This log is used to recover the system in case of problems in the disk.

The FAT32 system doesn’t have log of transactions. In case any problem happens in the disk (for example, the computer was turned off before completing a recording task) there won’t be any register of the last valid system configuration, which can result in a problem called cross-linked chains, that is when two or more files have the same clusters chain by mistake in FAT. For those reasons the FAT32 system is much more susceptible to problems than the NTFS.

Solving the Problem

In my case, where I had my computer’s file system corrupted, I was using Windows XP installed to a FAT32 partition.

You can solve problems in Windows XP file system by using the program CHKDSK that comes with Windows XP itself. To do so, use the following steps:

By using the procedure described above, I solved the problem in my computer’s file system. You can also use the Norton Disk Doctor utility from Norton Utilities pack to solve problems in your hard disk.

Originally at http://www.hardwaresecrets.com/article/Solving-Problems-in-Windows-XP-File-System/199


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