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Date:      Thu, 04 Dec 2014 17:11:39 +0000
From:      Arthur Chance <freebsd@qeng-ho.org>
To:        Andre Goree <andre@drenet.net>, Lowell Gilbert <freebsd-questions-local@be-well.ilk.org>
Cc:        FreeBSD Questions <freebsd-questions@freebsd.org>
Subject:   Re: Issue with swap file
Message-ID:  <548095CB.9070804@qeng-ho.org>
In-Reply-To: <3aff40bfeeb66db5cf30286a804ea5d0@drenet.net>
References:  <d37ad41e7e524b0547545ac5ae3c329a@drenet.net> <44fvcwgzaw.fsf@lowell-desk.lan> <2a3b7da1d03fd215ba1792e6617cfdb7@drenet.net> <44wq675qya.fsf@be-well.ilk.org> <3aff40bfeeb66db5cf30286a804ea5d0@drenet.net>

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On 04/12/2014 16:52, Andre Goree wrote:
> On 12/04/2014 11:18 am, Lowell Gilbert wrote:
>> Andre Goree <andre@drenet.net> writes:
>>
>>> On 12/03/2014 5:10 pm, Lowell Gilbert wrote:
>>>> Andre Goree <andre@drenet.net> writes:
>>>>
>>>>> Several months ago, I followed the procedure here[1] for creating a
>>>>> swap file.  This worked great for a long time, up until my last reboot
>>>>> which coincided with an update to 10.1.
>>>>>
>>>>> agoree@fbsd10-atl ~ % grep swap /etc/fstab
>>>>> md99            none            swap    sw,file=/usr/swap 0     0
>>>>> agoree@fbsd10-atl ~ % sudo swapon -a
>>>>> swapon: mdconfig (attach) error: md99 on file=/usr/swap
>>>>>
>>>>> I've also tried zero-writing the file again, to no avail.  Any ideas?
>>>>>
>>>>> [1] https://www.freebsd.org/doc/handbook/adding-swap-space.html
>>>>
>>>> Strange, I haven't run into any problems. And annoying that the error
>>>> message is so unhelpful. When that error message gets printed, swapon
>>>> has tried to run mdconfig and gotten an error back, but has no idea
>>>> what
>>>> the problem was. At that point, it has already checked that the md
>>>> device is available, which eliminates my best guess at a diagnosis.
>>>>
>>>> The way you can get more information is by running the mdconfig command
>>>> by hand, just as swapon would have, and see what *it* reports to you.
>>>>     mdconfig -a -t vnode -n -f /usr/swap
>>>>
>>>> Very likely, it will tell you exactly what to fix.
>>>
>>> I tried creating a new one (hence the '/usr/swap0' vs. '/usr/swap' in
>>> the output below) and still got the same error.  Here's the
>>> [disheartening] output from the command you gave:
>>>
>>> agoree@fbsd10-atl ~ % sudo swapon -a
>>> swapon: mdconfig (attach) error: md99 on file=/usr/swap0
>>> agoree@fbsd10-atl ~ % sudo mdconfig -a -t vnode -n -f /usr/swap0
>>> 0
>>
>> Okay, that means mdconfig can attach the file to an md device. That
>> eliminates my next guess, which was that md support wasn't working for
>> some reason (such as not being in your kernel configuration).
>>
>> The only difference I can see is the unit number, which I forgot to
>> include in the command. Maybe if you try
>>      mdconfig -a -t vnode -n -f /usr/swap -u 99
>> that will fail with an informative error message. If that doesn't help,
>> I'm baffled.
>
> Progress perhaps being made.
>
> agoree@fbsd10-atl ~ % sudo mdconfig -a -t vnode -n -f /usr/swap0 -u 99
> mdconfig: ioctl(/dev/mdctl): Device busy
> agoree@fbsd10-atl ~ % swapinfo
> Device          1K-blocks     Used    Avail Capacity
> agoree@fbsd10-atl ~ %
>
> Wtf? This is the newly created file too...
>

Have you tried "mdconfig -l" to see what existing md devs there are? 
Device busy often means "we've got one already".

-- 
Those who do not learn from computing history are doomed to
GOTO 1



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