Date: Sun, 09 Aug 2009 15:30:30 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: Michael Christie <vk3mrc@gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: (no subject) Message-ID: <4A7EDD86.3000608@infracaninophile.co.uk> In-Reply-To: <cfae10710908090538r34947c1an883003cfacc05a5c@mail.gmail.com> References: <cfae10710908090538r34947c1an883003cfacc05a5c@mail.gmail.com>
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Michael Christie wrote:
> Hi there all,
>=20
> I need your help. I have a supermicro server which was running Freebsd =
7.1
> with 2 SATA drives. I have had G mirror running on the server. I needed=
to
> do a full reinstall of freebsd but was unable to disengage the mirror a=
t the
> time. When installing Freebsd, on to the drives i see i have AD4 AD6 an=
d AR0
> on the disk label, i have installed the new free bsd in AD4, and the sy=
stem
> would not boot.
>=20
>=20
>=20
> I have come across this before where i have to remove AR0 to default th=
e
> drive, i can remember reading a thread on how to use =93fix it=94 and u=
sing the
> live cd. I have google but cannot find it
You do understand that 'ar0' is an ATARAID mirror and nothing to do with =
gmirror
at all? gmirror uses device names like /dev/mirror/gm0 typically.
> Please is there any one here that can refresh my memory and tell me how=
to
> remove gmirror from my drives so i can do a fresh install,.
You don't need to remove gmirror per-se. If you do a fresh install on to=
p
of what you have, it will set up the drive you install on as a stand-alon=
e
disk. In fact, you can take one of a gmirror'd pair and just tweak the d=
evice
names in /etc/fstab and run it as a plain disk pretty easily without rein=
stalling
at all.
There will be gmirror metadata blocks on disk, but these wont have any ef=
fect
unless you mount partitions on the gmirror device. To remove those metad=
ata
blocks, just do=20
# gmirror clear /dev/mirror/gm0
(or whatever your gmirror device is called) -- obviously *not* while the =
gmirror
is active. You may need to allow writes to an active underlying partitio=
n by
# sysctl kern.geom.debugflags=3D16
The ATARAID mirror you seem to have picked up inadvertently is very simil=
ar to
a gmirror RAID in the way it works, except that it won't generally have t=
he nice
behaviour for replacing blown hot-swap drives without having to reboot th=
e system.
In any case, you can just ignore /dev/ar0 and mount partitions from /dev/=
ad4=20
instead, equivalently as for the gmirror case. To remove ar0, just do:
# atacontrol delete ar0
Either of these are fairly safe to do while the system is up and running.=
Also, I suspect that your system is not booting for a different reason th=
an
you think. You'ld have to tell us the exact error message you see in ord=
er to
get a definitive answer, but given what you've described two pretty likel=
y
problems are:
* Early stage boot blocks can't find the kernel image. In this case
you'll be dumped at the loader prompt and asked to give the device
name and path to read the kernel from -- typically something like
=20
(ad,0)/boot/kernel/kernel
(you can use the 'ls' command in the loader to see what available d=
evices
there are to try booting from).
* Can't mount root partition. Generally this means that /etc/fstab c=
ontains
incorrect data. In this case, you can probably boot to single user=
, remount
the root partition read-write and then edit /etc/fstab=20
These are not impossibly difficult things to deal with, but neither are t=
hey
entirely trivial, and if you're a beginner and you don't care about what'=
s
currently on the disk, you might find it more productive just to reinstal=
l over
the top of the previous contents.
Cheers,
Matthew
--=20
Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard
Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
Kent, CT11 9PW
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