storing pdf files using filestream on file system

I am first time trying to use filestream to store pdf files on file system using varbinary(MAX) column type of DB.

I have followed following steps.

1. enabled filestream feature on SQL server 2008 R2.
2. Create a filegroup for BLOB storage
3. created table with blob column of type varbinary(max)

Now, I want to use file upload control to select file and when click on upload button it should save the pdf file. Also, how to retrieve the file?

I have tried following code

protected void btnFSupload_Click(object sender, EventArgs e)
    {
        SqlConnection cn = null;
        SqlTransaction tx = null;
        SqlCommand cmd = null;
        SqlCommand cmd2 = null;
        bool bCommit = false;

        try
        {
            // read in the file to be saved as a blob in the database
            FileStream input = new FileStream(@"D:\swami.pdf", FileMode.Open, FileAccess.Read);
            byte[] buffer = new byte[(int)input.Length];

            input.Read(buffer, 0, buffer.Length);

            cn = new SqlConnection("server=at-hetal01\\sqlexpress;Initial Catalog=practice;Integrated Security=true;");
            cn.Open();

            tx = cn.BeginTransaction();

            cmd = new SqlCommand("dbo.stp_AddBLOB", cn, tx);

            cmd.CommandType = System.Data.CommandType.StoredProcedure;

            SqlDataReader r = cmd.ExecuteReader(System.Data.CommandBehavior.SingleRow);

            r.Read();

            string id = r[0].ToString();
            string path = r[1].ToString();
            r.Close();  

            // get the transaction context
            cmd2 = new SqlCommand("SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()", cn, tx);
            Object obj = cmd2.ExecuteScalar();
            byte[] txCtx = (byte[])obj;

            // open the filestream to the blob
            SafeFileHandle handle = OpenSqlFilestream(path,DESIRED_ACCESS_WRITE,SQL_FILESTREAM_OPEN_NO_FLAGS,txCtx,(UInt32)txCtx.Length,0);

            // open a Filestream to write the blob
            FileStream output = new FileStream(handle,FileAccess.Write,buffer.Length,false);
            output.Write(buffer,0,buffer.Length);
            output.Close();

            if (handle != null && !handle.IsClosed)
                handle.Close();

            bCommit = true;
        }
        catch (Exception ex)
        {
            Response.Write(ex.Message);
        }
        finally
        {
            if (cn != null)
            {
                switch (bCommit)
                {
                    case true:
                        tx.Commit();
                        break;

                    case false:
                        tx.Rollback();
                        break;
                }

                cn.Close();
            }
        }

    }

Above code shows error as below

The operating system returned the error '0xc000003a({Path Not Found} The path %hs does not exist.)' while attempting 'NtCreateFile' on 'D:\DB\FS\d11132f8-c2a8-452d-ae0c-208164a550d7\beb8e1f1-8116-440b-870b-7cef4281a15d\0000001c-000000e4-010d'. The statement has been terminated.

So, any clue on this?

If you have altered your table using SSMS table designer, the FILESTEAM column attribute will be lost producing the path not found. Make sure the FILESTREAM attribute is set for the file field by running the follwoing statement in your database:

select SERVERPROPERTY('FilestreamShareName') as ShareName,
       SERVERPROPERTY('FilestreamConfiguredLevel') as ConfiguredLevel,
       SERVERPROPERTY('FilestreamEffectiveLevel') as EffectiveLevel

You'll need to alter the table via a script and NOT SSMS to tie your varchar(max)/filestream field to the FileGroup you should have already created.

When I ran into this issue, I found the answer on StackOverflow, but can't seem to find it again for the reference.