[Info-vax] INIT/HIGHWATER

[Rob Brown]

On Sat, 5 Feb 2011 at 13:57 -0000, Phillip Helbig---undress to reply wrote:

> How much of a performance hit is /HIGHWATER?

It was pretty bad 20--25 years ago.  I haven't had it turned on since 
then.  I suspect it would be much less noticeable these days.

> What about /ERASE?

INITIALIZE/ERASE or DELETE/ERASE?

Obviously INITIALIZE/ERASE is a one time operation, but is presumably 
going to take a while, since it erases the entire disk.  DELETE/ERASE 
obviously happens for each file delete.  If I thought it was 
important, I would not hesitate to use either of these.  But I am not 
in a place where I think it is important.  With the faster equipment 
we have these days, it will hurt a lot less.

I just did a quick test on an RZ40-AS on this DEC 3000-400 running VMS 
V7.1:

   delete a 100000 block file 0.14 seconds
   delete/erase a 100000 block file 13.55 seconds.

So that added .0001 seconds per block to the file deletion time on my 
system.  What does it do on your hardware?

fwiw


-- 

Rob Brown                        b r o w n a t g m c l d o t c o m
G. Michaels Consulting Ltd.      (780)438-9343 (voice)
Edmonton                         (780)437-3367 (FAX)
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