[Info-vax] OpenVMS Hobbyist licence - howto

[Chris Scheers]

Steven Schweda wrote:
> Michael Kraemer wrote:
>> This doesn't seem to be the complete explanation.
>> As the other poster has pointed out,
>> the problem already occurs at boot/installation time,
>> not just during a crash dump.
> 
> JF Mezei wrote:
>> Steven Schweda wrote:
>>
>>>    Which problem occurs where when?  There's no problem
>>> installing VMS on a disk bigger than 1GB,
>> The problem is that the first step of a clesn install is to use
>> standalone backup to move saveset B to the boot drive. Standalone backup
>> does not give you any flexibility on how it initialises the drive (for
>> instance, whether the critical structures are placed at the beginning,
>> middle or end of the disk).
>>
>> If the default is to place the structures at the middle of the drive,
>> and you have a 2,5gig drive or larger, this means that the critical
>> structures will be placed beyond the 1gb limit.
> 
>    Yes, but this causes no actual problem with either the
> installation or normal operation.  The disk corruption occurs
> when a crash dump corrupts the disk.
> 
>    One might argue that "the problem" is the installation of
> critical (dump) files in unfortunate places, and that this may
> occur during installation, but this is only one interpretation
> of "the problem", which is why I posed the question I did,
> namely, "Which problem occurs where when?".

FWIW:

The real problem is that the VS3100 console uses 6 byte SCSI commands to
address the disk.  Using 512 byte blocks, these commands can address 1GB
of disk.

Since VMS 5.3-2, DKDRIVER uses 10 byte SCSI commands, so it can address
a much larger disk.

The console SCSI driver is used to boot the system and to write the
crash dump, so the files it touches need to be in the first 1GB of the
disk.  The only writing done by the console SCSI driver (I think) is the
crash dump file, so that is the only file that actually causes corruption.

You can either use a 1GB or smaller drive for a VS3100 boot drive, or
you can partition and format a 1GB chunk at the front of a larger drive
and use the partition for your system drive.  (Note that there is no way
to do this with a standard VMS installation.)

For VMS 5.3-2 and later, this restriction does not apply to data disks.

-- 
-----------------------------------------------------------------------
Chris Scheers, Applied Synergy, Inc.

Voice: 817-237-3360            Internet: chris at applied-synergy.com
   Fax: 817-237-3074