the dump command, and then detaching the debugger without terminating it. Debugging can be done over a FireWire port and on a local system. The debug heap can be disabled and the standard heap be used when debugging. Vectored Exception Handling Windows XP introduces support for Vectored Exception Handling. Vectored Exception Handling is made available to Windows programmers using languages such as C++ and Visual Basic. VEH does not replace Structured Exception Handling (SEH), rather VEH and SEH coexist with VEH handlers having priority over SEH handlers. Compared with SEH, VEH works more like a traditional notification callback scheme. Applications can intercept an exception by calling the AddVectoredExceptionHandler API to watch or handle all exceptions. Vectored handlers can be chained in order in a linked list and they aren't tied to the stack frame, so they can be added anywhere in the call stack unlike SEH's try/catch blocks. Heap Heap leak detection can be enabled when processes exit and a debugger extension can be used to investigate leaks. Also introduced is a new heap performance-monitoring counter. Windows XP introduces a new low fragmentation heap policy (disabled by default) which allocates memory in distinct sizes for blocks less than 16KB to reduce heap fragmentation. The Low Fragmentation Heap can be enabled by default for all heaps using the LFH Heap Enabler utility. I/O There are new APIs for IRP cancellation and registering file system filter callbacks to intercept the OS fast I/O functions. In low memory conditions, "must succeed" calls are denied, causing a slowdown but preventing a bug check. I/O is throttled to fetch only one memory page at a time increasing overall scalability. File System Windows XP includes NTFS 3.1, which expands the Master File Table (MFT) entries with a redundant MFT record number, useful for recovering damaged MFT files. The NTFS conversion utility, Convert.exe, supports a new /CvtArea switch so that the NTFS metadata files can be written to a contiguous placeholder file, resulting in a less fragmented file system after conversion. NTFS 3.1 also supports symbolic links although there are no tools or drivers shipped with Windows XP to create symbolic links. Windows XP introduces the ability to mount NTFS read-only volumes. There are new APIs to preserve original short file names, to retrieve a list of mount points (drive letters and mounted folder paths) for the specified volume, and to enable applications to create very large