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From: dwb@well.UUCP (David W. Berry)
Newsgroups: net.micro.mac
Subject: Re: MAC filesystem vs UNIX filesystem
Message-ID: <1831@well.UUCP>
Date: Thu, 25-Sep-86 09:43:47 EDT
Article-I.D.: well.1831
Posted: Thu Sep 25 09:43:47 1986
Date-Received: Thu, 25-Sep-86 18:49:29 EDT
References: <8609232036.AA10451@cory.Berkeley.EDU>
Reply-To: dwb@well.UUCP (David W. Berry)
Organization: Whole Earth Lectronic Link, Sausalito CA
Lines: 23

In article <8609232036.AA10451@cory.Berkeley.EDU> dillon@CORY.BERKELEY.EDU (Matt Dillon) writes:
>
>>Jim Budler writes:
>>I hope you don't think that a Unix file is all physically contiguous.
>
>	Unix files are physically contiguous with the exception that you can,
>say, seek to position 11423444, do a write, and 11423444 bytes will actually
>NOT be physically allocated... the intermediate data between X and 1142344,
>when read, turns out to be zeros. (at least in BSD4.2)...  In fact, the
>DBM database utilities use this extensively.

	Just to be the first of many to point this out, Unix files
are rarely physically contigouus.  Logically yes, physically definitely
not.  Various versions of UNIX go to varying degrees of effort to
attempt to group the a file as contiguously as possible, but I know of
no version which will guarantee the physical contiguity of a file.


	David
-- 
	David W. Berry
	dwb@well.uucp                   dwb@Delphi
	dwb@GEnie                       293-0752@408.MaBell