Mail Archives: opendos/1997/12/17/05:50:41
On 97/12/16 Mark Aitchison wrote:
>Does verify=on only apply to diskettes?
>[...]
>I find diskette reads slower under DRDOS/Novell DOS/OpenDOS
>(haven't tried the 7.02B yet properly, so I'm interested in technical
>information of the improvements like the original poster).
VERIFY applies to the whole system, actually to all low level drivers
that support VERIFY. Since low level drivers can be replaced/enhanced
by loadable drivers, it also depends on a system s configuration. I have
not verified this in the sources right now, but I think, using OpenDOS
standard drivers, VERIFY applies to floppies and harddisks. (In the future,
there might be an option to selectively set VERIFY for each drive.)
Yes, uncached floppy disk writes are much slower under OpenDOS than under
MS-DOS. As far as I know, reads are about the same speed, with a little fuzz
depending on the system. I think the reason for this is tighter code combined
with bit more flexibility (some CP/M roots). Loading NWCACHE will almost
solve this limitation.
However, there have been no improvements concerning this from 7.01 to
7.02. I totally agree to set VERIFY ON if storing info on floppies. Pre-formatted
floppy disks are usually hard-formatted, that means, they have just the
"imprint" of a 100% error free medium, even if they are weak. I have made
the unsatisfactory experience, that about 5%-8% of no-name/low-priced "100%
error free" disks actually have defects. Setting VERIFY ON will detect most
of them (but not all). If you want to be (almost) sure, it is a good idea to always FORMAT /U new floppies (and put disks which do not reach the maximum
capacity into the bin - it will save you hours, if not days of work in the long run).
There are 3rd party formatters, which can format around weak spots on the
tracks (e.g. VGACOPY) by fiddling around with the format timing parameters.
Such formatted disks again reach the maximum capacity, and are more reliable
as long as not formatted by a standard formatter, but personally I still would
not want to use them. Todays hard disks are so reliable (and have internal
error recovery), that VERIFY OFF is absolutely OK (and will NWCACHE give
a chance to run up to maximum performance).
Matthias
------------------------------------------------------------
Matthias Paul
eMail: <Matthias DOT Paul AT post DOT rwth-aachen DOT de>
Web: http://www.rhrz.uni-bonn.de/~uzs180/mpdokeng.html
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