Fastest way to write raw data to hard drive (PhysicalDrive) on Windows 7

Question

My company is developing a "fancy" USB Mass Storage Device running under Windows 7.  The Mass Storage Client Driver that handles the reading and writing to the actual storage media on the client side is being written in C++. 
The problem we are having is very, very slow write speeds.  About 30 times slower than expected.  We are using calls to WriteFile() to write blocks of data to the storage media (specifically the physical drive 'PhysicalDrive2') as they are received
from the Host device.  I have read in many other forums that people have experience very slow write speeds using WriteFile() especially on Windows 7.  So I am trying to figure out if I am using the best method and function calls for this particular
task. 
Below are some blocks of code.  One for Disk_GetHandle() which gets a handle to the physical drive and is called only once.  One for LockVolume() function that gets called one time by the program during initialization.  The other block of
code is WriteSector() which is used to write the actual data to the physical drive when its received by the USB Client controller driver.  I am hoping that someone can shed some light on what I might be doing wrong or provided suggestions on a better
way to implement this.
UINT WriteSector(HANDLE hWriteDisk, PBYTE Buf, ULONG Lba, ULONG Blocks)
DWORD bytesWritten;
LPTSTR errMsg = "";
//setup overlapped structure to tell WriteFile function where to write the data
OVERLAPPED osWrite;
memset(&osWrite, 0, sizeof(osWrite));
osWrite.Offset = (Lba * SIZE_OF_BLOCK);
osWrite.hEvent = 0;
//write the data
if (!WriteFile(hWriteDisk, Buf, (Blocks * SIZE_OF_BLOCK), &bytesWritten, &osWrite))
DWORD Errorcode = GetLastError();
if (Errorcode == ERROR_IO_PENDING)
WaitForSingleObject(osWrite.hEvent, INFINITE);
else
FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), errMsg, 255, NULL);
printf("WriteSector() - WriteFile failed (%s)\n", errMsg);
goto exit;
if (bytesWritten != (Blocks * SIZE_OF_BLOCK))
printf("WriteSector() - Bytes written did not equal the number of bytes to be written\n");
return 0;
else
return Blocks;
HANDLE Disk_LockVolume(LPCWSTR _dsk)
HANDLE hVol;
LPWSTR errMsg;
DWORD status;
bool success = false;
//now try to get a handle to the specified volume so we can write to it
hVol = CreateFile(_dsk, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
//check to see if we were able to obtain a handle to the volume
if( hVol == INVALID_HANDLE_VALUE )
FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), errMsg, 255, NULL);
printf("Disk_LockVolume() - CreateFile failed (%s)\n", errMsg);
goto exit;
// now lock volume
if (!DeviceIoControl(hVol, FSCTL_LOCK_VOLUME, NULL, 0, NULL, 0, &status, NULL))
FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), errMsg, 255, NULL);
printf("Disk_LockVolume() - Error attempting to lock device! (%s)\n", errMsg);
goto exit;
//dismount the device
if (!DeviceIoControl(hVol, FSCTL_DISMOUNT_VOLUME, NULL, 0, NULL, 0, &status, NULL))
FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), errMsg, 255, NULL);
printf("Disk_LockVolume() - Error attempting to dismount volume. (%s)\n", errMsg);
goto exit;
exit:
return hVol;
HANDLE Disk_GetHandle(UINT Lun)
HANDLE hVol;
LPTSTR errMsg = "";
DWORD status;
bool success = false;
//now try to get a handle to the specified volume so we can write to it
hVol = CreateFile(MassStorageDisk[Lun].PhysicalDisk, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, 0, OPEN_EXISTING, FILE_FLAG_NO_BUFFERING, 0);
//check to see if we were able to obtain a handle to the volume
if( hVol == INVALID_HANDLE_VALUE )
FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL, GetLastError(),
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), errMsg, 255, NULL);
printf("Disk_WriteData() - CreateFile failed (%s)\n", errMsg);
return hVol;

Answer 1

Good for you for fixing the bug.  On the second go-round, I noticed another one, though.  You are not setting the hEvent handle on the OVERLAPPED structure.  If you ever do get an ERROR_IO_PENDING, it would probably be bad inside WriteFile,
but even if that returned, you would get a problem when calling WaitForSingleObject.
It helps that we know the actual WriteFile call is what is taking the time.  From your description, though, it's not clear what the precise issue is.  You are comparing write speeds of your SSD vs. a regular USB flash drive.  Are you also
comparing your program to that of another program?  If the comparison is just between SSD and the existing USB drive, why do you not believe you have established that IO on the SSD is slow? Your last sentence is confusing: you first say that the IO on
the USB drive was as expected and IO on the SSD was slower, then say that a file write unto the USB drive took 2.5 mins and copying it to the SSD took 2.5 seconds.  I assume these times were reversed.
BTW, personally for that kind of benchmarking, I would prefer non-buffered, synchronous IO myself.
I would also consider using
Process Monitor, for more information about what is going on with the low-level IO events.  Ignore the benchmarking numbers when procmon is running, but getting a log from it will give you more visibility into what events are firing and their sequence,
what flags the IFS is seeing, etc.