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Date:      Tue, 11 Dec 2001 00:08:39 EET
From:      Maxim Sobolev <sobomax@FreeBSD.org>
To:        dillon@apollo.backplane.com
Cc:        sheldonh@FreeBSD.org, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject:   Re: cvs commit: src/sbin/newfs newfs.8
Message-ID:  <200112102208.AAA18580@ipcard.iptcom.net>
In-Reply-To: <200112101846.fBAIkee47815@apollo.backplane.com>

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On Mon, 10 Dec 2001 10:46:40 -0800 (PST), Matthew Dillon wrote:
> :This is very questionable topic, at least from the space efficience
> :POV. For example, I found that on my development system using 16:2
> :(5-CURRENT, /usr/ports + /usr/src) some 300MB are wasted in fragments
> :compared with the same partition formatted with 8:1. I would suggest
> :to extend this para explaining that 16:2 could result in a huge space
> :wastage when there are large number of small files on the fs (such as
> :/usr/ports or /usr/src) and 8:1 is better suited for such cases.
> :
> :
> :-Maxim
> 
>     Interesting.  I just ran a test using VN for /usr/ports:
> 
> Filesystem  1K-blocks     Used    Avail Capacity  Mounted on	(512/4K)
> /dev/vn0c     3943361   114700  3513193     3%    /mnt
> 
> Filesystem  1K-blocks     Used    Avail Capacity  Mounted on	(1K/8K)
> /dev/vn0c     4065694   154837  3585602     4%    /mnt
> 
> Filesystem  1K-blocks     Used    Avail Capacity  Mounted on	(2K/16K)
> /dev/vn0c     4129310   251300  3547666     7%    /mnt
> 
>     So /usr/ports alone will eat 100MB of additional disk space on a
>     2K/16K filesystem, which is quite significant.
> 
> 
>     /usr/src has these characteristics:
> 
> Filesystem  1K-blocks     Used    Avail Capacity  Mounted on	(1K/8K)
> /dev/vn0c     4065694  1002597  2737842    27%    /mnt
> Filesystem  1K-blocks     Used    Avail Capacity  Mounted on	(2K/16K)
> /dev/vn0c     4129310  1046374  2752592    28%    /mnt
> 
>     /usr/src isn't so bad in my test, only 44 MBytes larger, which makes
>     sense because the average file size is larger then 1K anyway (so
>     2K/16K wins over 1K/8K for files > 1K and < 2K in size).
> 
>     I didn't think /usr/ports would lose so badly.  It is definitely food
>     for thought.  But I also think that /usr/src validates our prior
>     discussion for 'general purpose' filesystems.

Heh, now imagine that you have checkouted from our repo version of
/usr/ports - due to cvs metadata it has twice as much small files as
normal one, so amount of space wasted in 2K/16K case is also doubles,
resulting in some 200M wasted in fragments. This was exactly the case
here.

-Maxim

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