> > echo dma on >/dev/sdXX/ctl
> > echo rwm on >/dev/sdXX/ctl
> Inspired, I tried this, and I got an improvement (decrease)
> in time taken to copy files to a new filename of at least
> an order of magnitude.
> I was surprised to find the letters "rwm on" right at the
> beginning of the disk. I saved the output of
> I'm pretty sure that I did *not* type
>
> echo rwm on > /dev/sdC0/data /* WRONG */
I'm pretty sure that you did type
echo dma on >/dev/sdC0/ctl
echo rwm on >/dev/sdC0/data
explaining both the performance improvement
and the subsequently broken mbr.
The disk fragment you posted on the ftp server
begins with a standard NetBSD mbr except that
the first 7 bytes are "rwm on\n". This is perfectly
explained by a typo and very hard to explain with
a software or hardware error.
Once I set up a pseudo-worm file server on a few
SCSI disks, spent a few hours populating it, and then
rebooted and the kernel couldn't find the file system.
On inspection, I found postscript code in what should
have been the file server's superblock. That felt like a
hardware error (shouldn't use discarded machines;
people discard them for a reason!). This doesn't.
Russ
