How do you restart AIX in single-user mode?
David Choweller
Our RS/6000 320 AIX NFS server fails to mount a particular NFS volume
when starting up, and refuses to go past this point when restarting.
Is there anyway to force it to boot in single-user mode, so that we can
tell it not to automount this particular volume? I was thinking there'd
be some sequence of keystrokes to do this. (The shutdown or reboot
command wouldn't work, because we cannot type it in, as the system
hasn't started up yet.)
--
David Choweller (Office Hrs: W 3-4,F 3-4)
email: da...@cs.ucr.edu (Office: Bourns A-212, B-242)
Home page: http://olympia.ucr.edu/davec
Phone: 787-2961 (Bourns A-212), 787-2994 (Bourns B-242)
LAIXsoft
If you machine type has a key switch put it into service and boot from a
CD or
tape (install or mksysb tape). Start a limited function shell and type in
getrootfs hdisk# (where hdisk# is the hdisk which contains your boot
logical
volume - almost always hdisk0)... Voila, you're in a root shell.
Several ways to prevent this problem from occurring again:
1) put the "cons" line before the nfs line in the inittab so you get a
console login before you try starting NFS.
2) When adding nfs mounts via smit NFS select the soft mount option so
that it doesn't retry forever if the mount cannot be made... It just gives
up and moves on.
D. Dawbarn
>Several ways you can do this -
>If you machine type has a key switch put it into service and boot from a
>CD or
>tape (install or mksysb tape). Start a limited function shell and type in
>getrootfs hdisk# (where hdisk# is the hdisk which contains your boot
>logical
>volume - almost always hdisk0)... Voila, you're in a root shell.
>Several ways to prevent this problem from occurring again:
>1) put the "cons" line before the nfs line in the inittab so you get a
>console login before you try starting NFS.
This sounds like very good advice, but I note that it's not the way
it's set up by default. Anyone have any comments on whether there's
any reason one should *not* do this?
>2) When adding nfs mounts via smit NFS select the soft mount option so
>that it doesn't retry forever if the mount cannot be made... It just gives
>up and moves on.
I've heard (in this group) that soft mounting NFS file systems which are
mounted for read-write is a dangerous thing to do. Again, any comments?
Thanks.
-----------------------------------------------------------------------
| Mark Beauchamp Taylor - physicist trapped in a chemist's body. |
| mark....@bris.ac.uk http://zeus.bris.ac.uk/~chmbt/index.html |
| Department of Chemistry, University of Bristol, UK -------
-----------------------------------------------------| ... It's the future! |
------------------------
Clinton Pierce
>
> Our RS/6000 320 AIX NFS server fails to mount a particular NFS volume
> when starting up, and refuses to go past this point when restarting.
> Is there anyway to force it to boot in single-user mode, so that we can
> tell it not to automount this particular volume? I was thinking there'd
> be some sequence of keystrokes to do this. (The shutdown or reboot
> command wouldn't work, because we cannot type it in, as the system
> hasn't started up yet.)
>
Ok. If it's AIX 4.1, turn the key to "service" and reboot.
Eventually (it takes a few minutes) you'll get a menu, one of the options is
to boot in single user mode.
If it's <3.2.5, boot in service mode, go into the maintenance utilities, and
somewhere (it's been a while) is an option to get a single user shell. You
can then "getrootfs" to mount the root file system and fix it.
If it's =3.2.5, get out your boot diskettes. Didn't make any? Then a mksysb
tape will be fine. Put the machine in service mode, put the tape/disks in,
and wait. (and wait..and wait...and wait...) Eventually it'll bring up a menu
to install the OS. Option #4 will give you a root shell. Type "getrootfs" to
mount the root file system.
(I have a 3BT, a very fast AIX system, why does it take 10 friggin minutes to
reboot? And much longer if in maintenance mode... This is even before I see
things on the console. I can reboot a Sparc 20 in 30 seconds. I think reboot
time should be a benchmark consideration.... What do you think of that Austin?)
--
----------------------------------------------------------------------o------
Clinton A. Pierce | "If you rush a Miracle Man | \ / \ /
cpie...@ford.com | you get rotten miracles." | \ G /
DCI, Inc. on loan to Ford. | --Miracle Max, The Princess Bride | / \ / \
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Anton Dischner
> >2) When adding nfs mounts via smit NFS select the soft mount option so
> >that it doesn't retry forever if the mount cannot be made... It just gives
> >up and moves on.
>
> I've heard (in this group) that soft mounting NFS file systems which are
> mounted for read-write is a dangerous thing to do. Again, any comments?
>
> Thanks.
It's dangerous to mount it hard.
If the NFS-client is gone you will get no prompt if you reboot the machine.
Always use soft mount.
Best regards,
Toni
--
A. Dischner, AIX sysadmin, Oracle DBA | Maier's rule:
Institut fuer Klinische Chemie | Murphy is an
Klinikum Grosshadern | optimist.
Ludwig Maximilians Universitaet Muenchen, GER |
Marchioninistr.15 81366 Muenchen 49-89-70953202 |
Charlie McGuire
disc...@med.uni-muenchen.de (Anton Dischner) writes:
|> Hi,
|>
|> > >2) When adding nfs mounts via smit NFS select the soft mount option so
|> > >that it doesn't retry forever if the mount cannot be made... It just
|> gives
|> > >up and moves on.
|> >
|> > I've heard (in this group) that soft mounting NFS file systems which are
|> > mounted for read-write is a dangerous thing to do. Again, any comments?
|> >
|> > Thanks.
|>
|> It's dangerous to mount it hard.
|> If the NFS-client is gone you will get no prompt if you reboot the machine.
|>
|> Always use soft mount.
|>
don't care whether your writes actually complete or not). A hard NFS
mount request will time out on bootup if the server is unavailable.
You can adjust the timeout interval as well as the number of tries to
attempt the mount. In addition, you can set "interrupt" so you can
interrupt the mount request (^C). Once the client is up, you can
always clear out the NFS request and statd complaints. In general,
it's best to try and ensure reliability on the server side so the
mount doesn't fail to begin with (or at least happens rarely).
If your server or the link to it isn't reliable, then don't try
to use a writeable NFS mount at all.
Charlie
--
*************************************************************************
( Charlie McGuire | Tel. : (406) 243-4618 )
( System Administration | Fax : (406) 243-4076 )
( The University of Montana | )
( Computer Science Dept | E-Mail: mcg...@cs.umt.edu )
*************************************************************************
Allan Marillier
>
> David Choweller wrote:
> >
> > Our RS/6000 320 AIX NFS server fails to mount a particular NFS volume
> > when starting up, and refuses to go past this point when restarting.
> > Is there anyway to force it to boot in single-user mode, so that we can
> > tell it not to automount this particular volume? I was thinking there'd
> Eventually (it takes a few minutes) you'll get a menu, one of the options is
> to boot in single user mode.
And if it's one of the newer models - eg. E20 - PowerPC based - then it
has no keyswitch. Then, as per the docs that come with it, you need to
power on, and press the numeric 5 key when it starts all it's tests.
After a while, it will kick into single user booting ...
BUT ... watch out if you do as I did - and set the speed of the console
terminal and the relevant getty to 38400 - as you don't see the messages
indicating the SCSI, memory etc tests. To get around this, I had to set
the console speed back to 9600, watch for the messages, hit 5 a few
times, then quickly set the speed back to 38400, and then I could do it.
---
Allan Marillier
all...@iafrica.com
http://www.iafrica.com/~allanm
Lawrence Davis
inmaintence mode (Which technically you are in as a single user)
try the command (as root) 'init 4' or something like that, when your
ready to restart in multi user mode, issue: init 2
See /etc/inittab file init:2::initdefault
In article <3163DE...@ford.com>, Clinton Pierce <cpie...@ford.com> says:
>
>David Choweller wrote:
>>
>> Our RS/6000 320 AIX NFS server fails to mount a particular NFS volume
>> when starting up, and refuses to go past this point when restarting.
>> Is there anyway to force it to boot in single-user mode, so that we can
>> tell it not to automount this particular volume? I was thinking there'd
>> be some sequence of keystrokes to do this. (The shutdown or reboot
>> command wouldn't work, because we cannot type it in, as the system
>> hasn't started up yet.)
>>
>
>Ok. If it's AIX 4.1, turn the key to "service" and reboot.
>Eventually (it takes a few minutes) you'll get a menu, one of the options is
>to boot in single user mode.
>