| From: | The Hermit Hacker <scrappy(at)hub(dot)org> |
|---|---|
| To: | Tom <tom(at)sdf(dot)com> |
| Cc: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us>, mimo(at)interdata(dot)com(dot)pl, hackers(at)freebsd(dot)org, hackers(at)postgreSQL(dot)org |
| Subject: | Re: [HACKERS] sorting big tables :( |
| Date: | 1998-05-20 17:17:34 |
| Message-ID: | Pine.BSF.3.96.980520131553.14056W-100000@hub.org |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| 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(at)freebsd(dot)org for a "third
opinion"...am willing to admit I'm wrong *grin*
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