I know the speed differences and the advantage / disadvantage of each. My problem is that I cannot seem to find a way to directly access the devices and bypass all the caching and everything that occurs, because of this I cannot do what I need to and make sure writes occur in order at the time they are given.

I am at my wits end, I do not know where to go from here... My searches have shown that someone doing something similar needed to use mmap to map some memory and align it with something before using O_DIRECT. but the terminology is beyond me. I try using O_DIRECT and get an invalid argument.

Now I am trying it with O_SYNC but all it is doing is making it write at about 1mb every 2 minutes.

In reply to Re^2: Need writes to happen immediately. by exodist
in thread Need writes to happen immediately. by exodist

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.