[Info-vax] VSI roadmap

[Arne Vajhøj]

On 8/23/2023 5:43 PM, David Jones wrote:
> On Wednesday, August 23, 2023 at 4:24:17 PM UTC-4, Arne Vajhøj wrote:
>> On 8/23/2023 8:47 AM, David Jones wrote:
>>> I'm not sure that's true, given how slow hardware was 45 years ago. Adding
>>> 6 bytes of meta-data to a VAR file with an average record length of 30
>>> characters will increase the size by 18%. More space on disk and more I/O
>>> operations to process the file.
>> I am not sure that I can follow the math.
>>
>> Current VAR record overhead is header 2 bytes + average 0.5 even
>> pad byte and 2.5/30 is 8.3%.
>>
>> Increasing to 32 bit would mean header 4 bytes + average 0.5 even
>> pad byte and 4.5/30 is 15.0%.
>>
>> Increasing to 32 bit and add trailer length to support reading
>> backwards would mean header 4 bytes + average 0.5 even pad byte
>> + trailer 4 bytes and 8.5/30 is 28.3%.
>>
> 
> I was comparing data+overhead in the 8 byte case and 2 byte case:
> 128.3% / 108.3% = 118.46%

Ah. Got it.

>> Yes - it is some overhead. But NOS/VE is almost as old as
>> VMS and used header 6 bytes and trailer 6 bytes. They could
>> apparently live with it.
> 
> NOS/VE  is a 64-bit OS for CDC mainframes, quite a different animal than the
> VAX/VMS environment.

Maybe. But some universities actually had both.

Arne