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Date:      Sun, 20 Feb 2005 01:04:19 +0100
From:      Bernd Walter <ticso@cicely12.cicely.de>
To:        Eric Anderson <anderson@centtech.com>
Cc:        Matthew Jacob <lydianconcepts@gmail.com>
Subject:   Re: newfs limits? 10TB filesystem max?
Message-ID:  <20050220000418.GU14312@cicely12.cicely.de>
In-Reply-To: <4217BAC5.10504@centtech.com>
References:  <20050216224825.39102.qmail@web26807.mail.ukl.yahoo.com> <4213D046.4080001@centtech.com> <7579f7fb05021715344d661662@mail.gmail.com> <421605D0.80302@centtech.com> <20050218172831.GA9944@freebie.xs4all.nl> <4217BAC5.10504@centtech.com>

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On Sat, Feb 19, 2005 at 04:16:37PM -0600, Eric Anderson wrote:
> Wilko Bulte wrote:
> >On Fri, Feb 18, 2005 at 09:12:16AM -0600, Eric Anderson wrote..
> >
> >>Matthew Jacob wrote:
> >>
> >>>BTW- be careful with very large filesystems on FreeBSD- at some point
> >>>fsck can't check them.
> >>>
> >>>I built a sparse 5000TB filesystem which newfs'd and mounted okay, but
> >>>was not possible to check with fsck.
> >>
> >>5000TB?!?!   How did you do that? 
> >
> >
> >Note the word 'sparse' :)
> 
> 
> That doesn't explain it much.. Is there a doc on how to create these sparse 
> filesystems?

Creating sparse files, e.g. by using dd, is prety much unix basics.
And via md(4) you can get a disk type device from a file.

testdisk=/tmp/testdisk
dd if=/dev/zero bs=512 count=1 oseek=2m of=${testdisk}
mdev=`mdconfig -a -t vnode -f ${testdisk}`

I don't know if md(4) works with such large disks, but it's very likely
that is does.

-- 
B.Walter                   BWCT                http://www.bwct.de
bernd@bwct.de                                  info@bwct.de



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