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Date:      Thu, 20 Nov 2014 10:38:58 +0100
From:      =?iso-8859-1?Q?Jos=E9_Mar=EDa_Alcaide?= <jose@we.lc.ehu.es>
To:        "James R. Van Artsdalen" <james-freebsd-fs2@jrv.org>
Cc:        freebsd-fs@freebsd.org
Subject:   Re: BIOS booting from disks > 2TB
Message-ID:  <D91EAD51-2B6B-41E6-891E-575153409745@we.lc.ehu.es>
In-Reply-To: <546DA321.8050403@jrv.org>
References:  <17A2AC72-AD70-480A-9BAC-9CC8EAFD572F@we.lc.ehu.es> <alpine.BSF.2.11.1411191024540.55133@wonkity.com> <FF60956B-BF1F-4A1A-840E-489C549304EF@sarenet.es> <546DA321.8050403@jrv.org>

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> El 20/11/2014, a las 9:15, James R. Van Artsdalen =
<james-freebsd-fs2@jrv.org> escribi=F3:
>=20
>=20
> The extended BIOS disk functions, introduced onto PCs almost 20 years =
ago, allowing for addressing LBAs beyond 2TB.  FreeBSD will use these =
BIOS functions when present.  This is usually not a problem.
>=20
> If a disk controller card of some kind is installed then the option =
ROM on that card must support the extended BIOS disk functions for this =
to work.  This is usually not a problem.
>=20
> The error messages shown only pertained to the backup header, not =
primary, and looking at the code it implies to me that the primary =
header and table were read OK, and that these will be used even if the =
backup cannot be found.  I think "invalid backup GPT header" is a =
warning in this case, not a fatal error.
>=20
> I think the real problem is here:
>=20
> Can't work out which disk we are booting from.
> Guessed BIOS device 0xffffffff not found by probes, defaulting to =
disk0:
>=20
> 1. If you replace the 3TB disk with a disk 2TB or smaller and make no =
other change, does this error still happen?
>=20
> 2. How are the disks connected to the system?  What disk controllers =
are used?  What is the system BIOS boot disk setting set to?
>=20

I have an identical system (Proliant Microserver Gen8) with same =
hardware configuration, same firmware versions and same disks (WD Red 3 =
TB) as Borja's system.

When the disk controller is configured in AHCI mode there is no way of =
selecting the boot disk (among those connected to the disk controller). =
The BIOS only permits to select the boot disk controller, if there is =
more than one (which is not the case). So I think that the message

  Can't work out which disk we are booting from.
  Guessed BIOS device 0xffffffff not found by probes, defaulting to =
disk0:

is harmless (given that we actually want to boot from the first disk).

In fact I did another test: I installed FreeBSD on an 8 GB partition =
*using the MBR scheme instead of GPT*, and the system booted from the =
first 3 TB disk without any problem (and with four disks attached), =
despite of showing the same warning message.


--
Jose M. Alcaide=



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