| From: | Eivind Eklund <eivind(at)yes(dot)no> |
|---|---|
| To: | The Hermit Hacker <scrappy(at)hub(dot)org> |
| Cc: | hackers(at)FreeBSD(dot)ORG, hackers(at)postgreSQL(dot)org |
| Subject: | Re: [HACKERS] sorting big tables :( |
| Date: | 1998-05-20 20:44:30 |
| Message-ID: | 19980520224430.04725@follo.net |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
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| Lists: | pgsql-hackers |
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.
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