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Date: Thu, 15 Feb 1996 11:35:55 +0100
From: Wolfram Schneider <wosch@cs.tu-berlin.de>
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To: Greg W Hassan <gwhassan@cs.buffalo.edu>
CC: questions@freebsd.org
In-reply-to: Greg W Hassan's message of Wed, 14 Feb 1996 09:23:18 -0500
Subject: max file size/disk size?
Reply-to: Wolfram Schneider <wosch@cs.tu-berlin.de>
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>i'm looking for the max file size and the largest disk size?
>
>i have tried to calculate it but it seems too big.
>
>i believe the file size variable in the kernel is an
>unsigned long long, which would turn out to be 2^64. i think
>like 1.6 million terabytes.

[mmap(2) man page from -current]
The limit is imposed for a variety of reasons. Most of them have to do
with FreeBSD not wanting to use 64 bit offsets in the VM system due to
the extreme performance penalty. So FreeBSD use 32bit page indexes and
this gives FreeBSD a maximum of 8TB filesizes. It's actually bugs in
the filesystem code that causes the limit to be further restricted to
1TB (loss of precision when doing blockno calculations).