Block size on dumps (4.2BSD)

[Mike Williams]

Dump uses blocks of NTREC (defined in <dumprestor.h>) * 1024 bytes.
NTREC is defined as 10. For 1600 bpi this gives a tape "usage"
of about 90% (assuming that a block gap is 0.6 of an inch). 

However at 6250 bpi this becomes about 70% which is not so good. (ie I 
can't get a 130 Mbyte partition onto one tape). I tried increasing NTREC
to 20 and checked that dump and restore still worked, which they did.
NTREC of 20 gives about 84% usage. To get up to the 90% at 1600 bpi
you have to increase NTREC to 40. 

Having larger blocks increases the danger of a bad patch spoiling more of 
the dump, but are there any other obvious disadvantages?

Mike Williams
{decvax,philabs}!mcvax!enea!erix!mike or mike at erix.UUCP