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Date:      Fri, 14 Feb 2020 18:29:30 +0000
From:      Steve O'Hara-Smith <>
To:        Robert Huff <>
Cc:        tech-lists <>,
Subject:   Re: some questions about disk partitioning and filesystems and booting
Message-ID:  <>
In-Reply-To: <>
References:  <> <> <> <> <> <>

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On Fri, 14 Feb 2020 07:54:06 -0500
Robert Huff <> wrote:

> 	_If_ that's true, then it's a bug and needs to be fixed.  The
> folks posting here may not need it ... but I find it hard to imagine
> various organizations that use FreeBSD (or would like to) on hardcore
> server hardware wouldn't find that a substantial liability.
> 	While this may be more suited to hackers@: can anyone here
> confirm there is an encoded limit on swap space?

	According to this there is (or was at the time) a hard coded limit
of 32GB per swap device - just checked it's still there.

	You can of course have several swap devices - which is probably a
very good idea if you actually need more than 32GB of swap.

	Relevant text:

Anyway, there is one thing in /usr/src/sys/vm/swap_pager.c (so if you get
this warning (reducing size to maximum of... per swap unit)), this might be
the reason:

         * If we go beyond this, we get overflows in the radix
         * tree bitmap code.
        mblocks = 0x40000000 / BLIST_META_RADIX;
        if (nblks > mblocks) {
                printf("WARNING: reducing size to maximum of %lu blocks per
swap unit\n", mblocks);
                nblks = mblocks;

Steve O'Hara-Smith <>

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