From owner-freebsd-hackers Wed May 20 13:46:25 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id NAA21907 for freebsd-hackers-outgoing; Wed, 20 May 1998 13:46:25 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from ns1.yes.no (ns1.yes.no [195.119.24.10]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id NAA21622 for ; Wed, 20 May 1998 13:44:51 -0700 (PDT) (envelope-from eivind@bitbox.follo.net) Received: from bitbox.follo.net (bitbox.follo.net [195.204.143.218]) by ns1.yes.no (8.8.7/8.8.7) with ESMTP id UAA01952; Wed, 20 May 1998 20:44:31 GMT Received: (from eivind@localhost) by bitbox.follo.net (8.8.8/8.8.6) id WAA09099; Wed, 20 May 1998 22:44:31 +0200 (MET DST) Message-ID: <19980520224430.04725@follo.net> Date: Wed, 20 May 1998 22:44:30 +0200 From: Eivind Eklund To: The Hermit Hacker Cc: hackers@FreeBSD.ORG, hackers@postgreSQL.org Subject: Re: [HACKERS] sorting big tables :( References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.89.1i In-Reply-To: ; from The Hermit Hacker on Wed, May 20, 1998 at 01:17:34PM -0400 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Wed, May 20, 1998 at 01:17:34PM -0400, The Hermit Hacker wrote: > On Wed, 20 May 1998, Tom wrote: > > No, that doesn't happen. The only way to eliminate fragmentation is a > > dump/newfs/restore cycle. UFS does do fragmentation avoidance (which is > > reason UFS filesystems have a 10% reserve). > > Okay, then we have two different understandings of this. My > understanding was that the 10% reserve gave the OS a 'temp area' in which > to move blocks to/from so that it could defrag on the fly... No. What is done is (quite correctly) fragmentation avoidance. Big files are even sometimes fragmented on purpose, to allow small files that are written later to avoid being fragmented. Eivind. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message