[Info-vax] HP wins Oracle Itanium case

[Johnny Billquist]

On 2012-08-23 00:09, ChrisQ wrote:
> On 08/22/12 19:52, Johnny Billquist wrote:
>
>>
>> Uh... No. At the lowest level of a disk, you do *not* store a stream of
>> bytes. Where on earth did you get that from? At the lowest level, a disk
>> deals with disk *blocks*. You read/write one block at a time.
>> Blocks are typically 512 bytes, or possibly 2048 or 4096 bytes nowadays.
>
> Err, thanks, but I am aware of all that. It is a stream of bytes, it just
> happens to be formatted into blocks on the disk, for identification, error
> checking and recovery.

It's a disk block. You might then have implemented some abstraction 
layer on top of that, along with some metadata, to make it look like 
your disk provides you with a stream of bytes. But that is actually not 
the physical truth, but a lie presented to you with the help of a lot of 
software. And sometimes the truth shines through.

> If you read back in the thread, you'll see that what i'm really getting at
> is that a byte  stream is the most generic / lowest common denominator,
> from
> which all other data formats can be layered on top of.

Except you will get a block, and not a stream of bytes, when you read 
from a disk. If your "stream of bytes" supposedly were just 10 bytes, 
you would still get one block of bytes from the disk. The other 502 
bytes will also be something. You will then have to write a layer on top 
of the block nature of a disk to try and hide this truth.

And your assumption is even more not true when we come to tapes, which 
is why even Unix gave up on that idea there. Or are you telling me that 
you use the Unix tape block devices? (I've not met anyone in over 20 
years who do...)

And how about data communication using UDP? Do you think that is a 
stream of bytes too?

Simply put - some things works well to think of in streams of bytes. 
Other totally do not, and trying to do that actually breaks things, for 
no good reason.

> Since there are possibly an infinite number of data structures that you
> might
> want to develop in the future, it doesn't make sense to lock all that down
> within the file system itself...

It all needs to boil down to disk blocks eventually, if storing to disk.
Exactly what abstraction you place on top of that is up to you. But they 
are all abstractions, one way or another... And sometimes they work for 
you, and sometimes against you.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol