Thanks for your response. I included the use statements at the top of my post. Sorry, but I don't understand how these are incorrect- can you specify? They look quite similar to yours. Here is the relevant code in my program: 
#!/usr/bin/perl -w
use strict;
use Fcntl qw(O_RDWR O_CREAT); 
use MLDBM qw(DB_File Storable);
....
tie(%positions_hash, 'MLDBM', 'positions.db', O_CREAT|O_RDWR, 0640) or
+ die "Could not create db file\n"; #write positions hash to db file
untie %positions_hash;

[download]

The hash is a large, complex multi-level structure created in several subroutines which I didn't post. I suspect the problem has something to do with its size (> 1G). Your code, which is basically identical to mine except that the tied hash is a single-level small structure, also works fine on my system.

In reply to Re^2: MLDBM tie fails by greigite
in thread MLDBM tie fails by greigite

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.