Path: utzoo!attcan!uunet!edsews!rphroy!teemc!cfctech!norm
From: norm@cfctech.UUCP (Norm Meluch)
Newsgroups: comp.sys.next
Subject: Re: two passes to write file?
Keywords: passes writes
Message-ID: <337@cfctech.UUCP>
Date: 23 Nov 88 15:08:30 GMT
References: <25795@tut.cis.ohio-state.edu> <898@accelerator> <8711@spl1.UUCP> <4301@phoenix.Princeton.EDU> <900@paris.ics.uci.edu> <7592@pasteur.Berkeley.EDU> <7609@pasteur.Berkeley.EDU>
Reply-To: norm@cfctech.UUCP (Norm Meluch)
Organization: Chrysler Financial Corp., Troy, MI
Lines: 12

In article <7609@pasteur.Berkeley.EDU> woan@cory.Berkeley.EDU.UUCP
  (Ronald S. Woan) writes:
>>Actually I heard from a very reliable source that it takes three passes to
>>write a block.
>
>Yep, it takes one to erase, one to write, and one to verify; however, the erase
>is done when the machine isn't doing anything else....

Does this mean that a "DET" (disk erasure table) is kept somewhere on the 
disk to donote where the computer has had the spare time to erase, or is 
a FOURTH pass necessary to check that the area that the computer is about to
write on is clear?