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    <p>You need to tell us more about the hardware and operating system, also the specific Java version. How are you measuring this throughput?</p> <p>You're correct that force/sync should force the data out to the physical media.</p> <hr> <p>Here's a raw version of copy. Compiled with gcc 4.0 on an Intel Mac, should be clean.</p> <pre><code>/* rawcopy -- pure C, system calls only, copy argv[1] to argv[2] */ /* This is a test program which simply copies from file to file using * only system calls (section 2 of the manual.) * * Compile: * * gcc -Wall -DBUFSIZ=1024 -o rawcopy rawcopy.c * * If DIRTY is defined, then errors are interpreted with perror(3). * This is ifdef'd so that the CLEAN version is free of stdio. For * convenience I'm using BUFSIZ from stdio.h; to compile CLEAN just * use the value from your stdio.h in place of 1024 above. * * Compile DIRTY: * * gcc -DDIRTY -Wall -o rawcopy rawcopy.c * */ #include &lt;fcntl.h&gt; #include &lt;sys/types.h&gt; #include &lt;sys/uio.h&gt; #include &lt;stdlib.h&gt; #include &lt;unistd.h&gt; #if defined(DIRTY) # if defined(BUFSIZ) # error "Don't define your own BUFSIZ when DIRTY" # endif # include &lt;stdio.h&gt; # define PERROR perror(argv[0]) #else # define CLEAN # define PERROR # if ! defined(BUFSIZ) # error "You must define your own BUFSIZ with -DBUFSIZ=&lt;number&gt;" # endif #endif char * buffer[BUFSIZ]; /* by definition stdio BUFSIZ should be optimal size for read/write */ extern int errno ; /* I/O errors */ int main(int argc, char * argv[]) { int fdi, fdo ; /* Input/output file descriptors */ ssize_t len ; /* length to read/write */ if(argc != 3){ PERROR; exit(errno); } /* Open the files, returning perror errno as the exit value if fails. */ if((fdi = open(argv[1],O_RDONLY)) == -1){ PERROR; exit(errno); } if((fdo = open(argv[2], O_WRONLY|O_CREAT)) == -1){ PERROR; exit(errno); } /* copy BUFSIZ bytes (or total read on last block) fast as you can. */ while((len = read(fdi, (void *) buffer, BUFSIZ)) &gt; -1){ if(len == -1){ PERROR; exit(errno); } if(write(fdo, (void*)buffer, len) == -1){ PERROR; exit(errno); } } /* close and fsync the files */ if(fsync(fdo) ==-1){ PERROR; exit(errno); } if(close(fdo) == -1){ PERROR; exit(errno); } if(close(fdi) == -1){ PERROR; exit(errno); } /* if it survived to here, all worked. */ exit(0); } </code></pre>
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    2. COI wrote a 4 GB file using 64K blocks of the same random data and measured the time between file open and file close (and sync if it is done).
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    3. COAny other workload? The C was with GCC > 4? That configuration's similar to one I've tried at STK (RIP) and 120 MB/s sounds pretty plausible.
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