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Date:      Fri, 6 May 2011 01:29:57 -0500
From:      Kevin Day <toasty@dragondata.com>
To:        Marcel Moolenaar <marcel@xcllnt.net>
Cc:        freebsd-fs@freebsd.org
Subject:   Re: "gpart show" stuck in loop
Message-ID:  <4A043649-429E-4CAC-8DB2-2275ECF552A0@dragondata.com>
In-Reply-To: <6B7B3E48-08D5-47D1-85B4-FAA1EEE6764C@xcllnt.net>
References:  <C2BDEBA9-DD29-4B0B-B125-89B93F5997BA@dragondata.com> <FCA2B7F6-F9D1-4DA2-B22C-DEFBC1B55E1B@xcllnt.net> <6B7B3E48-08D5-47D1-85B4-FAA1EEE6764C@xcllnt.net>

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On May 5, 2011, at 10:11 PM, Marcel Moolenaar wrote:
> Hi Kevin,
>=20
> I reproduced the problem:
>=20

Yay!

> The first problem you have is that the MBR has overflows.
> As you can see from my initial MBR, only 2.0TB out of the
> 2.7T can be addressed, whereas yours addresses the whole
> 2.7T. There must be an overflow condition.
>=20
> The second problem is that more than 1 slice is marked
> active.

Yeah, I'm not exactly sure how the previous user of this storage array =
ended up with this MBR. I believe he was using it in FreeBSD, but =
probably something much older (6.x?). I don't know if it was actually =
working or not with all the partitions, but I honestly can't see how.

> I think we should do things:
> 1.  Protect the gpart tool against this,
> 2.  Fix the kernel to simply reject partitions that
>    fall outside of the addressable space (as determined
>    by the limitations of the scheme).
>=20
> In your case it would mean that slice 3 would result
> in slice 3 being inaccessable.
>=20
> Given that you've been hit by this: do you feel that such
> a change would be a better failure mode?

Definitely. As it stands now, slice 3 isn't accessible anyway:

# dd if=3D/dev/da0s3 of=3D/dev/null=20
dd: /dev/da0s3: Input/output error
0+0 records in
0+0 records out
0 bytes transferred in 0.000233 secs (0 bytes/sec)

So allowing the rc startup to finish without hanging would be much =
improved.

Thanks for the speedy answer. :)

-- Kevin




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