tailieunhanh - Windows Internals covering windows server 2008 and windows vista- P19

Windows Internals covering windows server 2008 and windows vista- P19: In this chapter, we’ll introduce the key Microsoft Windows operating system concepts and terms we’ll be using throughout this book, such as the Windows API, processes, threads, virtual memory, kernel mode and user mode, objects, handles, security, and the registry. | After it completes the redo pass NTFS begins its undo pass in which it rolls back any transactions that weren t committed when the system failed. Figure 11-55 shows two transactions in the log file transaction 1 was committed before the power failure but transaction 2 wasn t. NTFS must undo transaction 2. Suppose that transaction 2 created a file an operation that comprises three suboperations each with its own update record. The update records of a transaction are linked by backward pointers in the log file because they are usually not contiguous. The NTFS transaction table lists the LSN of the last-logged update record for each noncommitted transaction. In this example the transaction table identifies LSN 4049 as the last update record logged for transaction 2. As shown from right to left in Figure 11-56 NTFS rolls back transaction 2. LSN 41L44 Transaction 1 Transaction 2 Redo Set bits 3-9 in the bitmap Undo Clear bits S-9 in the bitrnap Reda Add the file name to the index Undo Remove the file name from the index Redo Ailocate initializean MFT file neoord Undo Deallocate the file record FliVRfi ll-Sfi Undoing a transaction After locating LSN 4049 NTFS finds the undo information and executes it clearing bits 3 through 9 in its allocation bitmap. NTFS then follows the backward pointer to LSN 4048 which directs it to remove the new file name from the appropriate file name index. Finally it follows the last backward pointer and deallocates the MFT file record reserved for the file as the update record with LSN 4046 specifies. Transaction 2 is now rolled back. If there are other noncommitted transactions to undo NTFS follows the same procedure to roll them back. Because undoing transactions affects the volume s file system structure NTFS must log the undo operations in the log file. After all the power might fail again during the recovery and NTFS would have to redo its undo operations When the undo pass of the recovery is finished the volume has been restored to a .

TỪ KHÓA LIÊN QUAN
crossorigin="anonymous">
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.