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Date:      Sun, 7 Jul 2002 01:13:46 +0200
From:      Bernd Walter <ticso@cicely5.cicely.de>
To:        Terry Lambert <tlambert2@mindspring.com>
Cc:        Darren Pilgrim <dmp@pantherdragon.org>, ticso@cicely.de, freebsd-hackers@FreeBSD.ORG
Subject:   Re: How does swap work address spacewise?
Message-ID:  <20020706231346.GJ23704@cicely5.cicely.de>
In-Reply-To: <3D2776BE.A39A1110@mindspring.com>
References:  <20020705113532.GA11273@atrbg11.informatik.tu-muenchen.de> <20020705133515.GA295@HAL9000.wox.org> <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>

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On Sat, Jul 06, 2002 at 04:01:18PM -0700, Terry Lambert wrote:
> Darren Pilgrim wrote:
> > > > I thought the limit for filesystems was 2TB?
> > >
> > > The Blocknumber is signed that gives:
> > > 2^31 * 512Bytes
> > 
> > Why sign the blocknumber?  LBA uses an unsigned 32-bit integer,
> > allowing 2TB, and IIRC SCSI uses an unsigned integer as well (though I
> > can't remember if that one is 32 or 48 bits, or if they've gotten to
> > 64 bits by now).
> 
> To differentiate between direct (positive) and indirect (negative)
> blocks within the inode, and within an indirect block.

Inodes hold fs blocks which are different from device blocks.
On UFS they are sized equaly to fragments.
And I never saw negative blocknumbers in inodes or indirect blocks.
The difference is made just with the location of the entry.
Do you have a special filesystem in mind?

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


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