硬盘读取速度很慢（Hard disk reads very slowly）

硬盘读取速度很慢（Hard disk reads very slowly） 硬盘读取速度很慢(Hard disk reads very slowly) The disk reads very slowly and is only about 4M/S with software testing, It was later found that there was a hard drive in the device manager, followed by USB Delete it, and then delete the IDE channel, reboot and return to normal. - - - - - - - - - - - - - - - - Extract a similar question online article, standby as follows: Computer, very slow, and then test the speed of hard disk only 3M., combined with the following article resolved, the speed reached more than 40 M, halo! SATA hard disk cannot open DMA mode - how to solve slow drive A customer said Thursday he drives very slowly. Starting in 10 minutes. 5 minutes off. Everything is normal. The hard disk scan the hard disk with the other machine scan is normal, no problem. Disc think the problem is not DMA. But now is the SATA disk. Then search + practice + test (somewhat crudely meaning) get such a way through practice test, problem solving is the problem. Set the DMA to introduce you: DMA mode of hard disk, we all should know, In general, our hard disk PATA modes are DMA33, DMA66, DMA100 and DMA133, SATA-150 has been out for a long time! In general, most people now use the PATA model of hard disk, the hard disk using DMA mode, compared to the previous PIO mode transmission speed 2~8 times faster. The use of the DMA mode has played a substantial role in the performance of the system. Many previous articles have introduced how to open DMA mode, I will not say more here. Most recently, we found that the new machines we bought were SATA's disk. It had a new "problem" - the WindowsXP and 2003 server systems sometimes shut down the DMA mode of the hard disk by themselves and automatically switched to PIO mode! This is caused by the sudden decline in the hard disk performance of the above systems, the most obvious of which is: The starting speed was slow, generally Windows XP when the system starts the normal movement of the slider from left to right up to 2 to 4 times the system will start, but this problem may take 5 to 8 times or more! But the hard disk in operation when running the system obviously feel slow, running in some large software CPU occupancy rate reached 100% and often pause, play some large-scale 3D games (such as the need for speed 6) screen when there is a noticeable pause (many people then thought the problem is the graphics, of course if you use their own three years ago the card playing these games is a bit old, but if you are using this year to buy GF card that is not the problem, the above problem) when you look at your best hard drive DMA mode is the Windows system automatically shut down. See if your system opens DMA mode: 1. double click the administrative tools, and then double-click the computer manager"; 2. click system tools, and then click device manager"; 3. expand the "IDE ATA/ATAPI controller" node; 4. double click your main IDE controller"; 5. click Advanced settings". See the "device 0, transmission mode below should be set to" DMA (if available), then the following current transmission mode, if it is "Ultra DMA Mode (* * digital, DMA33 2, DMA66 4, DMA100 5, DMA133 6), then your system is normal but, if you are set to the" Ultra DMA Mode 6 "have not changed, and now is" Ultra DMA Mode "Ultra DMA Mode 4" or 2 "or" PIO mode "and switch over! Maybe the system shut down the DMA model itself. Analysis problem: Let me start by talking about how the problem came about. In the Windows 2000/XP/2003 in such a setting: Windows IDE/ATAPI port driver (Atapi.sys) received a total of 6 cumulative time-out or cyclic redundancy check (CRC) error, the driver will take communication speed (transfer mode) access directly from the memory of the fastest (DMA) mode step by step dips to slow DMA mode. If the driver continues to receive a timeout or CRC error, The driver will eventually transfer the mode to the slowest mode (PIO mode). The problem is here! In general a normal hard disk will seldom have a timeout or a cyclic redundancy check (CRC) error, but when we use these systems in the hang (also called sleep) and recovery after the computer is very easy to cause a timeout or a cyclic redundancy check (CRC) error. Because the system set the timeout value of 4 seconds, when the system to the ATA disk read requests issued if the hard disk response time exceeds 4 seconds timeout will produce a timeout or a cyclic redundancy check (CRC) error, but because the system hangs on (also called sleep) when the hard disk is in the stopped state, recovery when a computer hard disk to the movement process from the stop, it is easy to cause most of the hard disk response time exceeds the time-out value of 4 seconds. That is to say, when we use the computer to hang 6 times, the system will split the communication speed (transfer mode) from the fastest direct memory access (DMA) mode to the slower DMA mode step by step. If you suspend more than 6 times, the driver will eventually transfer the mode to the slowest mode (PIO mode). That's why the Windows system suddenly slows down. Solve the problem: To reactivate a typical DMA or faster DMA transfer mode for affected devices, do the following: 1. double click the administrative tools, and then double-click the computer manager"; 2. click system tools, and then click device manager"; 3. expand the "IDE ATA/ATAPI controller" node; 4. double click the controller you want to restore the typical DMA transfer mode for; 5. click the driver tab; 6. click uninstall". When this process is complete, restart your computer. When the Windows is restarted, the hard disk controller is re enumerated, and the transfer mode of each device connected to the controller is reset to the default value. However, this simply resets the transfer mode of the hard disk device to the default, and when we use the pending system, the system closes the DMA mode itself! So we have to do the following: 1. click start, click Run, type Regedit, and then click ok". 2. find and click the following item in the registry: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E96A-E325-11CE-BFC1-08002BE10318}\0001 and HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E96A-E325-11CE-BFC1-08002BE10318}\0002 3. on the edit menu, point to new, and then click DWORD values". 4. type ResetErrorCountersOnSuccess, and then press the Enter key. 5. on the edit menu, click modify". 6. type L (number 1, do not write I or L), and then click ok". 7. follow these steps and exit the registry editor: Note: the main IDE channel above the registry "{4D36E96A-E325-11CE-BFC1-08002BE10318}" listed with the "0001" number corresponding to a computer with a IDE controller and a secondary IDE channel. If your computer has two IDE controllers, for each controller, the numbered sub items of the primary IDE channel and the minor IDE channel are: 0001, 0002, 0003, 0004, 0005, 0006......". To check if the correct subkey is found, check that the DriverDesc value of the subkey contains the string value, the primary IDE channel, or the string value, which is a secondary IDE channel". The purpose of creating the above registry key is: In Windows, the timeout value of 4 seconds for the system to issue a read request to the ATA disk is changed to 10 seconds. A less rigorous adaptation strategy is also implemented to reduce the transfer mode (from faster DMA mode to slower DMA mode and eventually to PIO mode in the event of timeout errors and CRC errors). The previous case was that the IDE/ATAPI port driver (Atapi.sys) would reduce the delivery mode whenever the cumulative timeout error or the total number of CRC errors reached 6. When we build the above registry key to implement the new policy, Atapi.sys only reduces the transfer mode only after 6 consecutive timeout errors or CRC errors. This new strategy will greatly reduce the opportunity for the system to reduce or turn off the DMA transfer mode. Now we can safely use the hang up system and the high-performance DMA hard disk mode, There will be no sudden drop in system performance If you think your machine is slow and find it is a hard disk problem, I suggest you try the following. Maybe you will have a good harvest