*BSD News Article 98527


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From: bde@zeta.org.au (Bruce Evans)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: ufs, ext2fs sizes
Date: 27 Jun 1997 03:43:50 +1000
Organization: Kralizec Internet
Lines: 33
Message-ID: <5ou9om$mqg$1@godzilla.zeta.org.au>
References: <33AF89E9.513B63BD@info13.polytechnique.fr> <5otrdo$dlh@ui-gate.utell.co.uk>
NNTP-Posting-Host: godzilla.zeta.org.au
Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:43570

In article <5otrdo$dlh@ui-gate.utell.co.uk>,
Brian Somers <brian@awfulhak.org, brian@utell.co.uk> wrote:
>In article <33AF89E9.513B63BD@info13.polytechnique.fr>,
>	ClimServ <climserv@info13.polytechnique.fr> writes:
>> - what is the maximum size of an ufs filesystem ?
>
>9223372036854775808 bytes.

Many wrong answers have been given to this question.  The limit is
2^31 * DEV_BSIZE, where DEV_BSIZE is normally 512, i.e., normally 1TB.

The file size is currently limited mainly by triple indirect blocks
never actually being allocated.  This gives a maximum file size of
about 32GB for a file system with a block size of 8K.

>> - if I choose ext2fs instead of ufs, can I take full advantage, under
>>   FreeBSD, of the Terabyte filesystem size of ext2fs ?
>
>Eh ?  A terabyte is relatively small !  What's the "full advantage" ?

ext2fs has the same file system size limit as ufs for the same reasons.

The file size for ext2fs is limited to 2^32 by the 32-bit size field
in the inode and to 2^31 by bugs in the code.

>> - are ext2fs tools (mke2fs, e2fsck) available under FreeBSD ?
>
>Not in my path (RELENG_2_2).

The Linux version of more or less work under the Linux emulator.  You have 
to give block counts explicitly because some ioctls don't work.
-- 
Bruce Evans  bde@zeta.org.au