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Date:      Sun, 7 Jul 2002 02:10:19 +0200
From:      Bernd Walter <ticso@cicely5.cicely.de>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        Bernd Walter <ticso@cicely5.cicely.de>, Terry Lambert <tlambert2@mindspring.com>, Darren Pilgrim <dmp@pantherdragon.org>, ticso@cicely.de, freebsd-hackers@FreeBSD.ORG
Subject:   Re: How does swap work address spacewise?
Message-ID:  <20020707001019.GK23704@cicely5.cicely.de>
In-Reply-To: <200207062342.g66NgMri063859@apollo.backplane.com>
References:  <20020705133837.GA513@HAL9000.wox.org> <20020705234126.GA12183@atrbg11.informatik.tu-muenchen.de> <3D2640A7.3EA2236B@pantherdragon.org> <20020706020656.GL48977@cicely5.cicely.de> <3D2762FE.9D9E0378@pantherdragon.org> <20020706220720.GG23704@cicely5.cicely.de> <3D277274.B5F3CE58@pantherdragon.org> <3D2776BE.A39A1110@mindspring.com> <20020706231346.GJ23704@cicely5.cicely.de> <200207062342.g66NgMri063859@apollo.backplane.com>

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On Sat, Jul 06, 2002 at 04:42:22PM -0700, Matthew Dillon wrote:
>     Negative block numbers are used by UFS to represent the indirect blocks
>     associated with a file, while positive block numbers represent the
>     contents of the file.

I never saw any negative block numbers in on-disc structures.
Now I wonder if it was just hidden behind macros.
What is the reason to handle it that way?
Do you have some code reference for homework?

>     These are logical block numbers, which are fragment-sized (1K typically).
>     So, 2^31 x 1K = 2TB.
> 
>     Physical block numbers are 512-byte sized, with a range of 2^32
>     in -stable.  This also winds up being 2TB.  So increasing the fragment
>     size does not help in -stable.

It's a proven fact that there is a 1T limit somewhere which was
explained with physical block numbers beeing signed.

-- 
B.Walter              COSMO-Project         http://www.cosmo-project.de
ticso@cicely.de         Usergroup           info@cosmo-project.de


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