From owner-freebsd-hackers  Fri Dec 10 12:17:38 1999
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Date: Fri, 10 Dec 1999 12:13:13 -0800 (PST)
From: Matthew Dillon <dillon@apollo.backplane.com>
Message-Id: <199912102013.MAA60500@apollo.backplane.com>
To: Zhihui Zhang <zzhang@cs.binghamton.edu>
Cc: freebsd-hackers@FreeBSD.ORG, freebsd-fs@FreeBSD.ORG
Subject: Re: Why VMIO directory is a bad idea?
References:  <Pine.GSO.3.96.991210135054.10820A-100000@sol.cs.binghamton.edu>
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:
:> :(3) Or maybe we can add a parameter to the filesytem, telling it to try to
:> :preallocate some contiguous disk space for all directory files. I guess
:> :that the cost per bit on disk is less than the cost per bit in memory.
:> 
:>     I believe the filesystem already does this.
:> 
:
:The FFS tries to allocate space contiguously for any type of file.  It
:does not PRE-allocate disk space, which will result wasteage of disk space
:if that space is not used later.
:
:-Zhihui

    I'm sorry, I misread that ... I thought he had said 'allocate'.  It
    definitely does not preallocate disk space.  FFS is designed to
    to avoid fragmentation so the blocks that it allocates when appending
    to a file (or directory) tend to be contiguous.

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>


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