FULL PRODUCT VERSION :
java version "1.7.0_03"
Java(TM) SE Runtime Environment (build 1.7.0_03-b04)
Java HotSpot(TM) 64-Bit Server VM (build 22.1-b02, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Linux XXX 3.0.0-21-generic #35-Ubuntu SMP Fri May 25 17:57:41 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
FileChannel.size() returns 0 for block devices on Linux. As a consequence, it is impossible to memory map a block device, because FileChannel.map() uses size() to determine whether the file is big enough, and in the case of a block device, since size() always returns 0, it always concludes that it isn't big enough, tries to enlarge it, and fails.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
On Linux, compile the sample code and execute it using a command similar to this:

sudo java -cp . BlockDeviceBug /dev/sda

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
It should show something like this:

File: /dev/sda
Size: 500107862016
Actual size: 500107862016
ACTUAL -
It actually says:

File: /dev/sda
Size: 0
Actual size: 500107862016

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class BlockDeviceBug {
    public static void main(String[] args) throws IOException {
        try (RandomAccessFile file = new RandomAccessFile(args[0], "r")) {
            FileChannel channel = file.getChannel();
            System.out.println("File: " + args[0]);
            System.out.println("Size according to FileChannel: " + channel.size());
            System.out.println("Actual size: " + file.length());
        }
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
No workaround found.