[Info-vax] HP wins Oracle Itanium case

[David Froble]

Johnny Billquist wrote:
> On 2012-08-22 15:05, ChrisQ wrote:
>> In the end though, what get's stored on disk is a stream of bytes at the
>> lowest
>> level. To make the most flexible use of that, an interface to that
>> stream should
>> be provided, even if there are other structures eg: rms, above. Someone
>> else
>> said that the qio interface could be used, but seem to remember that as
>> being
>> fairly arcane at the time.
> 
> 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.
> 
> I don't offhand feel safe enough to comment VMS specific here, but 
> atleast in RSX, QIO *is* the interface used to read/write blocks. RMS is 
> a library on top of this, and RMS uses QIO internally to actually 
> perform the disk activities.
> 
> As such, you can also implement any other file structure in RSX pretty 
> easily. You only need provide the same interface specified at the QIO 
> level, and you're set.
> 
> And actually, all the I/O operations done by RMS is done to the disk 
> device, but are in reality caught by the ACP, which then do the physical 
> I/O operations to the disk.
> So, write another ACP, that implements your file system, and just plug 
> it in, and off you go.
> 
>> I guess the argument is whether structure like rms should be integrated
>> into the
>> filesystem, or whether it should be a separate layer. Provided it's done
>> right,
>> either approach should be equally valid afaics...
> 
> I'm sure there must be some way of going around RMS in VMS, so is it 
> really integrated in the file system? Can't you dump a file as the disk 
> blocks doing analyze, for example. What relation do RMS have there, 
> since you are ignoring the file attributes, and process the blocks 
> exactly as they happen to be stored on the disk?
> 
>     Johnny
> 
> 

On ODS type disks, on VMS, it's my understanding that the directories are RMS 
files, or sort of ..   Thus the impression that VMS and RMS are tied together. 
In a way they are, but, it is possible to have other files, I do, and don't 
depend very much on RMS.  Used RMS for the filename parsing, no sense 
re-inventing the wheel, and if it changes, RMS will already be modified for you. 
  But after that, no calls to RMS.