Re: [HACKERS] sorting big tables :(
Marc G. Fournier <scrappy@hub.org>
From: The Hermit Hacker <scrappy@hub.org>
To: Tom <tom@sdf.com>
Cc: Bruce Momjian <maillist@candle.pha.pa.us>, mimo@interdata.com.pl, hackers@freebsd.org, hackers@postgreSQL.org
Date: 1998-05-20T17:17:34Z
Lists: pgsql-hackers
On Wed, 20 May 1998, Tom wrote: > > On Wed, 20 May 1998, The Hermit Hacker wrote: > > > One of the things that the Unix FS does is auto-defragmenting, at > > least the UFS one does. Whenever the system is idle (from my > > understanding), the kernel uses that time to clean up the file systems, to > > reduce the file system fragmentation. > > 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... Am CC'ng this into freebsd-hackers@freebsd.org for a "third opinion"...am willing to admit I'm wrong *grin*