Subject: Re: NetBSD, apple fibre-channel card & 2.8TB Xserve-RAID
To: None <>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: tech-kern
Date: 12/04/2004 00:16:06
>> Of course since the real limit in disklabels and FFS is 2^32 sectors
>> per partition and per filesystem

I've just run into some rather disturbing symptoms that lead me to
suspect the actual practical limit may be 1TB - ie, 2^31 sectors (of
half a K each).  Is anyone using filesystems over 1TB successfully?
How about with FFSv1?

I have no evidence, yet, that I haven't already presented.  I have some
tests to run, but this is very recent and I haven't yet run them.  This
came from a discussion with a friend, very recently - we suspect there
is something going wonky at the 1TB mark, either it's reading/writing
the wrong sectors, or the buffer cache is getting confused, or some
such.  The most likely candidate to my mind is some kind of 32-/64-bit
bug, possibly sign-extending when it should be zero-extending, or maybe
using a 32-bit datatype (maybe inadvertently) where a 64-bit type is
called for.

But much of the weirdness I recently reported on tech-kern with
directories that appear fine to fsck but the kernel acts bizarre with
can be rather neatly explained by assuming such bugs in the block
device code paths, or perhaps the filesystem disk-interface code paths.

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