Re: Dr Dobbs article on kernel level database

On Mon, Apr 14, 2008 at 8:59 PM, Mike Cunningham <mcunning@xxxxxxx> wrote:

The latest edition of Dr Dobbs magazine had an article about the "first ever" database engine embedded in the kernel of an Operating System. I know that "kernel" does not always mean "OS" but I also know that a lot of people use the terms to mean the same thing. I also know that since the S/38 days IBM has said that DB2/400 is part of OS/400 (aka i5/OS, i/OS). Could DB2/400 also be considered as being part of the "kernel" of i5/OS - i/OS?

This is almost philosophical in nature. But in general, a Kernel is
the "core" of an Operating System - it provides the most essential
functions on which applications can build to get a fully featured
operating system. I wouldn't equalize a kernel with "OS".

For Windows, Linux, etc. making the difference between Kernel and
Userspace is pretty easy. The kernel is a pretty small part that
interfaces with the hardware, and everything builds on top of that.
All Linux distributions use variations of the same Kernel, with a
different userspace layered on top of it.

Windows Vista and Windows Server 2008 both have the same kernel (with
different configurations), but with a different userspace.

Windows has an HTTP server that is implemented partly in kernel space (IIS).

MS SQL Server has it's own runtime that circumvents a lot of OS
functions (like caching etc.)

i5/OS has a bit of a different architecture - while there are many
parts that are clearly userspace (e.G. DGM, IP1, WDS, etc. pp.), the
LIC is a lot more than a kernel - for example it offers the Java JVM
and of course DB/2. I'm not familiar enough with i5/OS - i'm sure
somewhere part of the LIC is a kernel (most probably a microkernel),
but the architecture can't be compared directly.

Compared to SQL Server on Windows, the i5/OS architecture seems superior.