Subject: Re: a thought about FFS parameters & disk performance
To: Soren S. Jorvang <soren@t.dk>
From: Curt Sampson <cjs@portal.ca>
List: current-users
Date: 03/30/1997 16:24:07
On Mon, 31 Mar 1997, Soren S. Jorvang wrote:

> What I meant was, I got similar performance from 'dd bs=8k' and
> 'dd bs=64k', as would be expected with a smaller MAXPHYS.

Oh, and now you get better. I see. Well, that's fair enough. I
personally don't think that what appears, off-hand, to be a 10-15%
speed increase is worth the loss of disk space, but that's obviously
a personal decision.

> For general use, I mostly use 4K fragments. I do not have seperate
> partitions for source, so I do not see the waste you describe.

It's not a matter of separate partitions for source; I was just
using that filesystem as an example because it typically has at
least 60,000 files on it. With waste averaging .5K/file I loose 30
MB or so of disk space. With waste averaging 2K or 4K/file, I loose
60 or 120 MB of disk space.

(Actually, that figure was quite old. A current count, now that
I've got a few more checkouts and some source trees for other OSs
and the like, gives me just under 300,000 files using about 3 GB
of disk space. Currently about 150 MB (5%) of that would be wasted
space; that would go up to 300 MB (10%) with 2K fragments or 600
MB (20%) with 4K fragments.

cjs

Curt Sampson    cjs@portal.ca		Info at http://www.portal.ca/
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