Re: High throughput disk write: CreateFile/WriteFile?

From:

"Alexander Nickolov" <agnickolov@mvps.org>

Newsgroups:

microsoft.public.vc.language

Date:

Tue, 3 Jul 2007 11:16:14 -0700

Message-ID:

<#813#4ZvHHA.4332@TK2MSFTNGP06.phx.gbl>

In that case the failure is due to your not writing in blocks of
multiples of the sector size. That at least should be clear from
the doucmentation on FILE_FLAG_NO_BUFFERING!

--
=====================================
Alexander Nickolov
Microsoft MVP [VC], MCSD
email: agnickolov@mvps.org
MVP VC FAQ: http://vcfaq.mvps.org
=====================================

"Brandon" <killerhertz@gmail.com> wrote in message
news:1183384445.616956.291790@c77g2000hse.googlegroups.com...

On Jul 2, 1:09 am, Tim Roberts <t...@probo.com> wrote:

How can we possibly know that without knowing what error you are getting?
There was nothing inherently wrong with the code you posted.

I apologize. When I use FormatMessage(...) and GetLastError(),
WriteFile(...) is returning:

"The parameter is incorrect." Seems ambiguous...

Unless, that is, you opened the file with FILE_FLAG_OVERLAPPED. If you
open a file overlapped, then EVERY I/O function must specify an overlap
structure.

I'm only opening the file with the FILE_FLAG_NO_BUFFERING flag.

Here's my current code snippet:

<SNIP>
               // Write ASCII header to file.
               sprintf_s(szTemp, sizeof(szTemp),
                   "MyData: Date:%s\r\n", szTimeStamp);
               if (! WriteFile(
                   hWriteFile,
                   szTemp,
                   sizeof(szTemp),
                   &dwNumBytesWritten,
                   NULL) )
               {
                   // Get the error message.
                   DWORD dwChars = FormatMessage(
                       FORMAT_MESSAGE_FROM_SYSTEM |
FORMAT_MESSAGE_ALLOCATE_BUFFER,
                        0,
                        GetLastError(),
                        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                        (LPSTR) &lpszErr,
                        0,
                        0);
                   // Append it to the log.
                   pThis->UI->AppendToStatLog(lpszErr);
                   pThis->UI->AppendToStatLog("WARNING:
FileWriteThread - Writing header line 1 to file!");
               }
</SNIP>