## PHP, <s>60</s> 30 bytes ##
Updated as per @manatwork suggested:

 while(file_put_contents(1,1));


----------
A bit of cheating 25 bytes

<s>while(exec('>1 echo 1'));</s>


NOT TESTED (no php available on this computer) 43 bytes:

<s>for($a=fopen(1,'w');fputs($a,1);fclose($a))</s>

A golfed original 45 bytes:

<s>$a=fopen(1,'w');while(fputs($a,1))rewind($a);</s>

My first post here, joined because I just had to try this out: as long as file write succeeds, rewind file pointer to start.

----------
Just can't get smaller than the file_put_contents().