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Date:      Sat, 7 Feb 2004 07:59:50 +1100
From:      Peter Jeremy <PeterJeremy@optushome.com.au>
To:        Claus Guttesen <cguttesen@yahoo.dk>
Cc:        freebsd-current@freebsd.org
Subject:   Re: Reserved space (WAS: How to calculate bsdlabel size)
Message-ID:  <20040206205950.GU908@cirb503493.alcatel.com.au>
In-Reply-To: <20040206084458.53207.qmail@web14101.mail.yahoo.com>
References:  <20040206072244.GT908@cirb503493.alcatel.com.au> <20040206084458.53207.qmail@web14101.mail.yahoo.com>

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On Fri, Feb 06, 2004 at 09:44:58AM +0100, Claus Guttesen wrote:
>>> But it's not my problem. What you mean results in
>>> limited available space,
>>> but doesn't have any influence on Size summary.
>>> Btw I did a newfs with -m 0
>>> so it can't be the reaseon.
>> 
>> This is strongly non-recommended.  The UFS
>> algorithms are designed on
>> the assumption that there are always free blocks. 
>> When you get below
>> 5-10% free space, the performance will degrade
>> significantly and you
>> will start getting file fragmentation.
>> 
>
>Does the algorithm(s) rely only on percentage of free
>space? On a five TB (netto) filesystem eigth percent
>is approx. 410 GB which seems quite alot.

In general, yes.  See /usr/share/doc/smm/05.fastfs/paper.ascii.gz
You might be able to get away with a lower minfree in some circumstances
depending on your filesystem activity pattern.

Peter



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