Increase fragment size to block size

Increase fragment size to block size

The underlying storage pool actually uses multiple block
size.  Under Solaris frsize (fragment size) is reported as
the smallest block size we support, and bsize (block size)
as the filesystem's maximum block size.  Unfortunately,
under Linux the fragment size and block size are often used
interchangeably.  Thus we are forced to report both of them
as the filesystem's maximum block size.

Closes #112