A few problems with BSD

[Chris Torek]

In article <10194 at eddie.MIT.EDU> nessus at athena.mit.edu (Doug Alan) writes:
>The following are a few problems I've had with 4.3BSD on a uVax II ....

>   (1) If you accidentally attempt to boot a system on a disk drive
>	for which there is no partition table in the kernal, BSD kindly
>	trashes the filesystem for you.

The 4.3BSD UDA50 driver treats unknown disks as type `ra81'.  I
considered this bogus; the 4.3BSD-tahoe driver considers them to
be of type `unknown' (and then gives you a chance to label them).
This does not help much with non-DEC MSCP disks, which generally
claim themselves to be RA81s anyway.

>   (2) It appears that the BSD bootblocks will not boot a kernal that
>	is bigger than a certain size.  This happened to me, and it was
>	very frustrating to figure out what the problem was.  I finally
>	replaced the BSD bootblocks with the Ultrix bootstrap system,
>	and this fixed things.

The 4.3BSD bootblock will not work at all on a MicroVAX II.  You have
to have been using an old Ultrix bootblock.

>   (3) In the partition table for a disk drive, a "-1" for the size of
>	a partition is supposed to mean that the partition contains
>	everything up to the end of the disk.

Yes.

>	It seems, however, that this only works if the disk is less than
>	a certain size.

No.  Any negative number translates into `reported size - partition
offset'.  If the disk reports its size incorrectly, VMS does not work,
so no disks report their sizes incorrectly.

>I also have a more academic question: A BSD filesystem is supposed to
>begin on a cylinder boundary for performance reasons.  Is swap space
>also supposed to begin a cylinder boundary, or does it make no
>difference?  I know there's "tunefs", and there's tuna fish, but
>there's no "tuneswap"....

It hardly matters, but if everything else starts and ends on a cylinder
boundary, the free region(s) left over for swap space will do so as well.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris at mimsy.umd.edu	Path:	uunet!mimsy!chris