我们已经基于此Code Project创建了一个项目，并已升级到Visual Studio2017。但是，我们修改了C＃DotNet部分，以备份到Azure Block Blob。它必须是一个块Blob，以便以后添加加密。 CPP DotNet代码将缓冲区传递到64KB缓冲区中的C＃部分。 C＃部分将多个64KB块合并为一个大的50MB块，然后再上传到Azure。由于Azure块Blob中的块数大约有50K限制，因此需要组合缓冲区。对于大型数据库，上传为64KB的块将使我们很快超过该限制。
这一切都像魅力一样。但是，它的速度非常慢：与管理Studio中等效的BACKUP TO URL相比，备份80GB数据库的时间大约要长3倍。
这是从C＃传递到CPP VDI子系统的命令：
BACKUP DATABASE [bench1] TO VIRTUAL_DEVICE='<deviceGUID>' WITH FORMAT,COMPRESSION
性能的下降似乎在于将64KB的块合并为50MB的块。我的问题：是否有一种方法可以强制VDI子系统返回大于64KB的缓冲区，还是“内置于调味料中”？
这是非常精简的VDIDotNet.CPP代码。为简洁起见，大多数错误处理已被删除。
#include "vdi.h"
#include "vdierror.h"
#include "vdiguid.h"
using namespace System;
using namespace System::Data;
using namespace System::Data::Odbc;
using namespace System::Globalization;
using namespace System::IO;
using namespace System::Runtime::InteropServices;
using namespace System::Threading;
using namespace System::Reflection;
namespace VdiDotNet {
public ref class VdiEngine
{
private: Void SqlServerConnection_InfoMessage(Object^ sender,OdbcInfoMessageEventArgs^ e)
{
VdiDotNet::InfoMessageEventArgs^ i = gcnew VdiDotNet::InfoMessageEventArgs(e->Message);
InfoMessageReceived(this,i);
}
private: Void ThreadFunc(Object^ data)
{
try
{
String^ connString = "Driver={SQL Server Native Client 11.0};Server=(local);Trusted_Connection=Yes;";
//Create and configure an ODBC connection to the local SQL Server
OdbcConnection^ SqlServerConnection = gcnew OdbcConnection(connString);
SqlServerConnection->InfoMessage += gcnew OdbcInfoMessageEventHandler(this,&VdiDotNet::VdiEngine::SqlServerConnection_InfoMessage);
//Create and configure the command to be issued to SQL Server
OdbcCommand^ SqlServerCommand = gcnew OdbcCommand(data->ToString(),SqlServerConnection);
SqlServerCommand->CommandType = CommandType::Text;
SqlServerCommand->CommandTimeout = 0;
//Notify the user of the command issued
CommandIssued(this,gcnew CommandIssuedEventArgs(data->ToString()));
//Open the connection
SqlServerConnection->Open();
//Execute the command
SqlServerCommand->ExecuteNonQuery();
}
catch (Exception ^ex)
{
LogException(ex);
throw gcnew ApplicationException(ex->Message);
}
}
private: static Void ExecuteDataTransfer (IClientVirtualDevice* vd,Stream^ s)
{
VDC_Command * cmd;
DWORD completionCode;
DWORD bytesTransferred;
HRESULT hr;
while (SUCCEEDED(hr = vd->getcommand(INFINITE,&cmd)))
{
array<System::Byte>^ arr = gcnew array<System::Byte>(cmd->size);
bytesTransferred = 0;
switch (cmd->commandCode)
{
case VDC_Read:
// ... stuff ...
case VDC_Write:
//Copy the data from the cmd object to a CLR array
Marshal::Copy((IntPtr)cmd->buffer,arr,cmd->size);
//Write the data to the stream
s->Write(arr,cmd->size);
//Set the number of bytes transferred
bytesTransferred = cmd->size;
//Set the completion code
completionCode = ERROR_SUCCESS;
break;
case VDC_Flush:
//Flush the stream
s->Flush();
//Set the completion code
completionCode = ERROR_SUCCESS;
break;
case VDC_ClearError:
//Set the completion code
completionCode = ERROR_SUCCESS;
break;
default:
//Set the completion code
completionCode = ERROR_NOT_SUPPORTED;
break;
}
//Complete the command
hr = vd->CompleteCommand(cmd,completionCode,bytesTransferred,0);
}
}
public: Void ExecuteCommand(System::String^ command,Stream^ commandStream)
{
try
{
//Initialize COM
HRESULT hr = CoInitializeEx(NULL,COINIT_MULTITHREADED);
//Get an interface to the virtual device set
IClientVirtualDeviceSet2* vds = NULL;
hr = CoCreateInstance(CLSID_MSSQL_ClientVirtualDeviceSet,NULL,CLSCTX_INPROC_SERVER,IID_IClientVirtualDeviceSet2,(void**)&vds);
//Configure the device configuration
VDConfig config = { 0 };
vds->getconfiguration(INFINITE,&config);
config.deviceCount = 1; //The number of virtual devices to create
//Create a name for the device using a GUID
String^ DeviceName = System::Guid::NewGuid().ToString()->ToUpper(gcnew CultureInfo("en-US"));
WCHAR wVdsname[37] = { 0 };
Marshal::Copy(DeviceName->ToCharArray(),(IntPtr)wVdsname,DeviceName->Length);
//Create the virtual device set
hr = vds->CreateEx(NULL,wVdsname,&config);
//Format the command
command = String::Format(gcnew CultureInfo("en-US"),command,DeviceName);
//Create and execute a new thread to execute the command
Thread^ OdbcThread = gcnew Thread(gcnew ParameterizedThreadStart(this,&VdiDotNet::VdiEngine::ThreadFunc));
OdbcThread->Start(command);
//Configure the virtual device set
hr = vds->getconfiguration(INFINITE,&config);
//Open the one device on the device set
IClientVirtualDevice* vd = NULL;
hr = vds->OpenDevice(wVdsname,&vd);
//Execute the data transfer
ExecuteDataTransfer(vd,commandStream);
//Wait for the thread that issued the backup / restore command to SQL Server to complete.
OdbcThread->Join();
}
catch (Exception ^ex)
{
LogException(ex);
throw gcnew ApplicationException(ex->Message);
}
}
};
}
这是精简后的VDI.H
#include "rpc.h"
#include "rpcndr.h"
#include "windows.h"
#include "ole2.h"
#pragma pack(8)
struct VDConfig
{
unsigned long deviceCount;
unsigned long features;
unsigned long prefixZonesize;
unsigned long alignment;
unsigned long softFileMarkBlockSize;
unsigned long EOMWarningSize;
unsigned long serverTimeOut;
unsigned long blockSize;
unsigned long maxIODepth;
unsigned long maxTransferSize;
unsigned long bufferAreaSize;
} ;
enum VDCommands
{ VDC_Read = 1,VDC_Write = ( VDC_Read + 1 ),VDC_ClearError = ( VDC_Write + 1 ),VDC_rewind = ( VDC_ClearError + 1 ),VDC_WriteMark = ( VDC_rewind + 1 ),VDC_SkipMarks = ( VDC_WriteMark + 1 ),VDC_SkipBlocks = ( VDC_SkipMarks + 1 ),VDC_Load = ( VDC_SkipBlocks + 1 ),VDC_GetPosition = ( VDC_Load + 1 ),VDC_SetPosition = ( VDC_GetPosition + 1 ),VDC_Discard = ( VDC_SetPosition + 1 ),VDC_Flush = ( VDC_Discard + 1 ),VDC_snapshot = ( VDC_Flush + 1 ),VDC_Mountsnapshot = ( VDC_snapshot + 1 ),VDC_PrepareToFreeze = ( VDC_Mountsnapshot + 1 ),VDC_FileInfoBegin = ( VDC_PrepareToFreeze + 1 ),VDC_FileInfoEnd = ( VDC_FileInfoBegin + 1 )
} ;
struct VDC_Command
{
DWORD commandCode;
DWORD size;
DWORDLONG position;
BYTE *buffer;
} ;
谢谢您的建议。