Subject: Re: SCSI/disklabel questions
To: Michael Wolfson <firstname.lastname@example.org>
From: Jason Thorpe <email@example.com>
Date: 06/29/1998 00:04:08
On Sun, 28 Jun 1998 12:29:10 -0400 (EDT)
Michael Wolfson <firstname.lastname@example.org> wrote:
> As for the SCSI speed business, I should've been a little more clear:
> I've never seen more than ~700 KB/s under normal usage (tar, cp, mv, ftp).
> Using dd to read and write null data, I can indeed get 1.5 MB/s, but
> that's still 1/2 the thruput I get on other platforms.
That's mainly because the controller driver does not support synchronous
> In any case, David Brownlee mentioned that SCSI could be noticably faster
> once we get the machine independent SCSI drivers ported to hp300. So,
> this is kind of moot if that happens anytime soon. Same goes for the DAT
> issue (i.e. apparently most DAT drives would be supported with MI SCSI).
Strictly speaking, using the MI SCSI code would not speed up your transfers.
That is purely a controller driver issue. (Yes, the controller driver needs
to be rewritten from scratch.)
However, your observation about supporting most DAT drives is correct.
> To: email@example.com
> Subject: SCSI/disklabel questions
> How are the bootblocks and disklabel arranged? As best as I can
> determine, the label sits at sector 1, and the boot blocks surround it
> at sector 0 and 2 thru whatever. This would make sense since improperly
> installed boot blocks can be wiped out by disklabel and vice versa.
That is correct, the disklabel lives "inside" the boot block.
> The install notes recommend ofsetting the a partition by one cylinder,
> which is fine for disks with small cylinder sizes, but how much space
> is really necessary for SCSI disks?
...as much as it takes to keep the boot block (which spills into the C
partition, making it FS_BOOT) from spilling into the A partition.
> What other NetBSD platforms can/can't write disklabel and bootblocks for
> hp300 machines (I know sun3x, sun3, and sparc can't)?
Huh? sun3x, sun3, sparc, and hp300 can all write boot blocks to the disks
and write disklabels to the disk.
> And, lastly, can anyone comment on why the HP-IB isn't available when one
> or more SCSI devices are attached (i.e. can't use HP-IB drives or
> tapes if a SCSI drive is plugged into my 400s)? This used to work
> thru NetBSD-1.1.
"Um, I don't know." I have used HP-IB and SCSI at the same time on my
hp380. Define "can't use" .. they don't probe, a timeout occurs when they
are accessed, what? I need specifics here :-)
Jason R. Thorpe firstname.lastname@example.org
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