Peter Jeremy peter at rulingia.com
Fri Sep 13 18:00:09 AEST 2019

On 2019-Sep-13 15:54:32 +1000, Dave Horsfall <dave at horsfall.org> wrote:
>On Thu, 12 Sep 2019, Larry McVoy wrote:
>> But here is an SCCS win.  SCCS has a 16 bit ignore the carry bit 
>> checksum over the whole file.  RCS has none of that.
>Giggle...  I found I could actually *edit* an SCCS file, provided I reset 
>the checksum to zero (it was then recalculated).

I think that was deliberate.  ISTR editing SCCS files and repairing the
checksum as well, though I don't recally exactly how.

>> B) NFS errors.  So all NFS implementations, Suns included, had a bad 
>> habit of returning a block of nulls.  I dunno why but that is a thing. 
>> The SCCS checksum would detect that.  RCS and CVS did not have a 
>> checksum so when NFS returned garbage, they were happy to return that to 
>> you.
>I believe that NFS is much more reliable now (yes, it used to be awful).

NFS ran much faster when you turned off the UDP checksums as well.
(Though there was still the Ethernet CRC32).

Peter Jeremy
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