How can I create a RAM disk programmatically?

Question

I am not looking for a code that invokes a command line utility, which does the trick. I am actually interested to know the API used to create a RAM disk.

EDIT

Motivation: I have a third party library which expects a directory name in order to process the files in that directory in a certain way. I have these files zipped in an archive. I wish to extract the archive into a RAM disk and pass the third party the path to the respective directory on that RAM disk. As you can see, memory mapped files are of no use to me.

Answer 1

ImDisk is a RAM disk app that creates a virtual drive from a sector of memory, and has an API that can be called from .NET.

class RamDisk
{
    public const string MountPoint = "X:";

    public void createRamDisk()
    {

        try
        {
            string initializeDisk   = "imdisk -a ";
            string imdiskSize       = "-s 1024M ";
            string mountPoint       = "-m "+ MountPoint + " ";


            ProcessStartInfo procStartInfo  = new ProcessStartInfo();
            procStartInfo.UseShellExecute   = false;
            procStartInfo.CreateNoWindow    = true;
            procStartInfo.FileName          = "cmd";
            procStartInfo.Arguments         = "/C " + initializeDisk + imdiskSize + mountPoint;
            Process.Start(procStartInfo);

            formatRAMDisk();

        }
        catch (Exception objException)
        {
            Console.WriteLine("There was an Error, while trying to create a ramdisk! Do you have imdisk installed?");
            Console.WriteLine(objException);
        }

    }

    /**
     * since the format option with imdisk doesn't seem to work
     * use the fomat X: command via cmd
     * 
     * as I would say in german:
     * "Von hinten durch die Brust ins Auge"
     * **/
    private void formatRAMDisk(){

        string cmdFormatHDD = "format " + MountPoint + "/Q /FS:NTFS";

        SecureString password = new SecureString();
        password.AppendChar('0');
        password.AppendChar('8');
        password.AppendChar('1');
        password.AppendChar('5');

        ProcessStartInfo formatRAMDiskProcess   = new ProcessStartInfo();
        formatRAMDiskProcess.UseShellExecute    = false;
        formatRAMDiskProcess.CreateNoWindow     = true;
        formatRAMDiskProcess.RedirectStandardInput     = true;
        formatRAMDiskProcess.FileName           = "cmd";
        formatRAMDiskProcess.Verb               = "runas";
        formatRAMDiskProcess.UserName           = "Administrator";
        formatRAMDiskProcess.Password           = password;
        formatRAMDiskProcess.Arguments          = "/C " + cmdFormatHDD;
        Process process                         = Process.Start(formatRAMDiskProcess);

        sendCMDInput(process);
    }

    private void sendCMDInput(Process process)
    {
        StreamWriter inputWriter = process.StandardInput;
        inputWriter.WriteLine("J");
        inputWriter.Flush();
        inputWriter.WriteLine("RAMDisk for valueable data");
        inputWriter.Flush();
    }

    public string getMountPoint()
    {
        return MountPoint;
    }
}

Answer 2

you didnt mentioned the language , sO my answer is in c# :

A memory-mapped file contains the contents of a file in virtual memory. This mapping between a file and memory space enables an application, including multiple processes, to modify the file by reading and writing directly to the memory. Starting with the .NET Framework version 4, you can use managed code to access memory-mapped files in the same way that native Windows functions access memory-mapped files, as described in Managing Memory-Mapped Files in Win32 in the MSDN Library.

http://msdn.microsoft.com/en-us/library/dd997372.aspx

MemoryMappedFile MemoryMapped = MemoryMappedFile.CreateOrOpen(
       new FileStream(@"C:\temp\Map.mp", FileMode.Create), // Any stream will do it      
       "MyMemMapFile",                                     // Name
       1024 * 1024,                                        // Size in bytes
       MemoryMappedFileAccess.ReadWrite);                  // Access type

// Create the map view and read it:

using (MemoryMappedViewAccessor FileMap = MemoryMapped.CreateViewAccessor())
{
       Container NewContainer = new Container();
       FileMap.Read<Container>(4, out NewContainer);
}

Answer 3

WinFsp allows you to define your own file system programmatically, using plain c++ or also dotNet C#. The example project is a file system persisted in OS RAM memory. You may also take a look at Dokany.

https://github.com/billziss-gh/winfsp

https://github.com/dokan-dev/dokany

Answer 4

There is no API to create a RAM disk per se. You need to write your own device driver which presents a new disk to the system, and make that device driver work with allocated memory.

EDIT (after the OP's edit)

What you are trying to do would normally be done using the 'temp' directory, which is supposed to reside on the fastest disk available in the system. So, a system which already has a RAMdisk will probably have its temp environment variable already set to point to a folder on the RAMdisk, and systems without a RAMdisk would simply take the performance penalty, it is their problem.

Now, if for some reason you cannot rely on the presence of a RAMdisk on a system, AND you absolutely need the fastest performance possible, then I see no option but to install a third-party (perhaps freely downloadable, perhaps even open source) RAM disk, use it temporarily, and then uninstall it. But that's very clunky.