[Info-vax] questions on initialize/gpt

[Dirk Munk]

Stephen Hoffman wrote:
> On 2015-06-21 13:54:31 +0000, Dirk Munk said:
>
>> I just read the chapter on the DCL initialize command,
>
> Go read <http://labs.hoffmanlabs.com/node/209> and
> <http://labs.hoffmanlabs.com/node/112> for an intro, and then
> <http://labs.hoffmanlabs.com/node/28> for far more details on the
> low-level structures and organization.
>
>>  and there it says:
>>
>>  >> When /GPT is specified, the system file [000000]GPT.SYS is
>> created. GPT.SYS contains partition/boot information needed by the
>> IA64 console software. (GPT is an abbreviation for GUID Partition
>> Table, where GUID stands for Global Unique Identifier.) <<
>>
>> That seems to suggest the disk gets a industry standard GUID Partition
>> Table, or not?
>
> Yes.  The ODS-2/5 GPT.SYS file "protects" the GPT structures; it
> overlays the structures.   Other ODS-2/5 files are used to "protect"
> other partitions that can be present, as well.
>
>> But then you would expect to be able to take a partition on an
>> existing   disk with a GPT label, and format it with ODS-2 or ODS-5,
>> but I can't find any information on that.
>>
>> What is going on here?
>
> What's going on is that ODS-2 and ODS-5 are overlaid across the entire
> disk including across the GUID partition table (GPT) data structures at
> the front (low-numbered sector addresses) and back (high addresses) of
> the disk, centrally because the OpenVMS bootstrap and the OpenVMS device
> drivers and some associated and ancillary pieces such as MOUNT do not
> support disk partitioning.
>
> This has been discussed several times before, of course.
>
> I'd hope that VSI would implement partitioning support at some point,
> but they've not discussed it.
>
>
Perhaps that will come with the new filesystem?