Subject: RE: Network throughput and upgrading kernel questions
To: 'Peter Svensson' <>
From: Antonio Carlini <>
List: port-vax
Date: 05/03/2003 14:15:12
> I think (my vms vaxen are in storage) that vms supports=20
> larger disks. One=20
> needs to tweak a bit in one of the scsi mode pages for vms to=20
> like the=20
> disk though. The auto-remap must be turned off. At least for older=20
> versions of vms.=20

Yes but the ~1GB is nothing to do with VMS - it's a limitation
of the console rom used during booting. VMS also uses the rom's drivers
during a crash to write to the dump file. Any reads or writes beyond
the 1GB reach of the console rom's 6-byte SCSI commands wrap. For a
read that means you don't get what you want and you probably hang or
crash pretty quickly. For a write, something random just got=20
overwritten - which is probably much worse!

Arranging for all the necessary bits to live within the first
1GB on affected systems (all VAXstation 3100s, and any MicroVAX
3100 Model 10/20s that didn't get the console upgrade) is quite=20
tricky for VMS, although it can be done. On NetBSD it's easier
since you can partition the disk as you wish (although I've never
tried doing this on an affected system).

> Hm, from a quick check on google it appears that the limit in=20
> early vms=20
> (up to 5.5-2) was 8GB.

Yes, V6 raised the OS limit to 1TB or so. I guess that looked
big then too :-)



Antonio Carlini