serial console over the network

Hi,

On Tue, April 15, 2008 4:40 pm, Ahmed Kamal wrote:
> Hi guys,
>
> Situation
> =======
> I'm managing a server in some rural area with too many
power cuts! Even long
> power cuts that our ups can't handle, and sometimes
flickery power spikes,
> such that evidently sometimes the server reboots, and
waits at the stupid
> "check file system" prompts. I get to drive
for an hour to fix that FS
> corruption! Now, that machine does not have IPMI
management or similar, and
> the serial port is connected to the UPS for
auto-shutdown.
> Problem
> =====
> This leaves me with no "remote" way to fix
serious errors such as FS
> checking
> Suggestion
> =======
> Is there such a thing as remote serial console. I'm
thinking *if* the kernel
> gets to boot, then it immediately starts the network
interface, and a tiny
> server for sending console messages to whoever is
connected. I should be
> able to fix FS corruption and other serious problems.
My question is, does
> such a thing exist ?

  You might want to look into KVM-over-IP....

HTH,

Mike

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Ahmed Kamal wrote:
> <snip>
> Is there such a thing as remote serial console. I'm
thinking *if* the 
> kernel gets to boot, then it immediately starts the
network interface, 
> and a tiny server for sending console messages to
whoever is 
> connected. I should be able to fix FS corruption and
other serious 
> problems. My question is, does such a thing exist ?
Insert a serial card so you have multiple serial ports,
configure your 
system to use a serial console and use a cyclades (over
ssh).  I have 
been telecommuting at least two days a week and this setup
works great.

-darren

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On Tuesday 15 April 2008 05:40:08 pm Ahmed Kamal wrote:
> Hi guys,
>
> Situation
> =======
> I'm managing a server in some rural area with too many
power cuts! Even
> long power cuts that our ups can't handle, and
sometimes flickery power
> spikes, such that evidently sometimes the server
reboots, and waits at the
> stupid "check file system" prompts. I get to
drive for an hour to fix that
> FS corruption! Now, that machine does not have IPMI
management or similar,
> and the serial port is connected to the UPS for
auto-shutdown.
> Problem
> =====
> This leaves me with no "remote" way to fix
serious errors such as FS
> checking
> Suggestion
> =======
> Is there such a thing as remote serial console. I'm
thinking *if* the
> kernel gets to boot, then it immediately starts the
network interface, and
> a tiny server for sending console messages to whoever
is connected. I
> should be able to fix FS corruption and other serious
problems. My question
> is, does such a thing exist ?

Yes. Serial-over-LAN is a feature on many IPMI-equipped
systems. I believe 
both the OpenIPMI-tools and freeipmi packages have a means
by which to 
connect to them, but I'm not all that familiar with either
one myself.

$ rpm -qf /usr/sbin/ipmiconsole
freeipmi-0.5.1-3.fc9.x86_64

$ ipmiconsole --usage
[...]

$ rpm -qf /usr/bin/ipmitool
OpenIPMI-tools-2.0.13-2.fc9.x86_64

$ ipmitool -h 2>&1 |grep sol
	sol           Configure and connect IPMIv2.0
Serial-over-LAN
	tsol          Configure and connect with Tyan IPMIv1.5
Serial-over-LAN
	isol          Configure IPMIv1.5 Serial-over-LAN

-- 
Jarod Wilson
jwilsonredhat.com

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On Tuesday 15 April 2008 05:51:40 pm Jarod Wilson wrote:
> On Tuesday 15 April 2008 05:40:08 pm Ahmed Kamal
wrote:
> > Hi guys,
> >
> > Situation
> > =======
> > I'm managing a server in some rural area with too
many power cuts! Even
> > long power cuts that our ups can't handle, and
sometimes flickery power
> > spikes, such that evidently sometimes the server
reboots, and waits at
> > the stupid "check file system" prompts.
I get to drive for an hour to fix
> > that FS corruption! Now, that machine does not
have IPMI management or
> > similar, and the serial port is connected to the
UPS for auto-shutdown.
> > Problem
> > =====
> > This leaves me with no "remote" way to
fix serious errors such as FS
> > checking
> > Suggestion
> > =======
> > Is there such a thing as remote serial console.
I'm thinking *if* the
> > kernel gets to boot, then it immediately starts
the network interface,
> > and a tiny server for sending console messages to
whoever is connected. I
> > should be able to fix FS corruption and other
serious problems. My
> > question is, does such a thing exist ?
>
> Yes. Serial-over-LAN is a feature on many IPMI-equipped
systems. I believe
> both the OpenIPMI-tools and freeipmi packages have a
means by which to
> connect to them, but I'm not all that familiar with
either one myself.
>
> $ rpm -qf /usr/sbin/ipmiconsole
> freeipmi-0.5.1-3.fc9.x86_64
>
> $ ipmiconsole --usage
> [...]
>
> $ rpm -qf /usr/bin/ipmitool
> OpenIPMI-tools-2.0.13-2.fc9.x86_64
>
> $ ipmitool -h 2>&1 |grep sol
> 	sol           Configure and connect IPMIv2.0
Serial-over-LAN
> 	tsol          Configure and connect with Tyan IPMIv1.5
Serial-over-LAN
> 	isol          Configure IPMIv1.5 Serial-over-LAN

D'oh, pardon my stupidity. I read that as "that machine
does have IPMI" 
instead of does not. Cyclades or similar serial console
server hooked to a 
serial port on the machine is the answer then.

-- 
Jarod Wilson
jwilsonredhat.com

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Ahmed Kamal wrote:
> Hi guys,
> 
> Situation
> =======
> I'm managing a server in some rural area with too many
power cuts! Even long
> power cuts that our ups can't handle, and sometimes
flickery power spikes,
> such that evidently sometimes the server reboots, and
waits at the stupid
> "check file system" prompts. I get to drive
for an hour to fix that FS
> corruption! Now, that machine does not have IPMI
management or similar, and
> the serial port is connected to the UPS for
auto-shutdown.
> Problem
> =====
> This leaves me with no "remote" way to fix
serious errors such as FS
> checking
> Suggestion
> =======
> Is there such a thing as remote serial console. I'm
thinking *if* the kernel
> gets to boot, then it immediately starts the network
interface, and a tiny
> server for sending console messages to whoever is
connected. I should be
> able to fix FS corruption and other serious problems.
My question is, does
> such a thing exist ?

Something you might keep an eye out for in the future is
USB-capable 
UPSs. Or since the serial cable doesn't actually seem to do
you any 
good, remove it and attach a modem instead.

(wonders about security; I suppose that can be handled.
Yeah, there are 
ways).



-

Cheers
John

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On Tuesday 15 April 2008 09:02:35 pm John Summerfield
wrote:
> Ahmed Kamal wrote:
> > Hi guys,
> >
> > Situation
> > =======
> > I'm managing a server in some rural area with too
many power cuts! Even
> > long power cuts that our ups can't handle, and
sometimes flickery power
> > spikes, such that evidently sometimes the server
reboots, and waits at
> > the stupid "check file system" prompts.
I get to drive for an hour to fix
> > that FS corruption! Now, that machine does not
have IPMI management or
> > similar, and the serial port is connected to the
UPS for auto-shutdown.
> > Problem
> > =====
> > This leaves me with no "remote" way to
fix serious errors such as FS
> > checking
> > Suggestion
> > =======
> > Is there such a thing as remote serial console.
I'm thinking *if* the
> > kernel gets to boot, then it immediately starts
the network interface,
> > and a tiny server for sending console messages to
whoever is connected. I
> > should be able to fix FS corruption and other
serious problems. My
> > question is, does such a thing exist ?
>
> Something you might keep an eye out for in the future
is USB-capable
> UPSs.

Could also move the existing ups to a usb-to-serial adapter,
which would allow 
the on-board serial port to serve as a serial console
output.

Doesn't help you in the least right now, but note that the
idea has been 
tossed around in Fedora kernel land about making basic
usb-serial support 
built into the kernel in rawhide post-Fedora 9 release, the
primary reason 
being so that one could do serial console output on a
usb-serial adapter...


-- 
Jarod Wilson
jwilsonredhat.com

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On Wednesday 16 April 2008 05:55:32 am John Summerfield
wrote:
> Jarod Wilson wrote:
> > Doesn't help you in the least right now, but note
that the idea has been
> > tossed around in Fedora kernel land about making
basic usb-serial support
> > built into the kernel in rawhide post-Fedora 9
release, the primary
> > reason being so that one could do serial console
output on a usb-serial
> > adapter...
>
> This is a bit related, so I'll bring it up here, and
maybe again on
> Fedora test.
>
> I have a problem with 2.6.25 kernels on one of my
systems, and so I've
> been playing with ways to get stuff logged. The
netconsole looks handy,
> but I've not managed to get it to work.
>
> I don't want to assign an IP address in the kernel
commandline, so it
> has to get one.
>
> At present, it doesn't do this, so netconsole doesn't
work.
>
> Just for the hell of it, I added "ip=dhcp" as
one does for nfs-root.
>
> Then, netconsole failed. After that, the kernel used
dhcp to get an IP
> address.
>
> Now, if the kernel could get the IP address first, then
netconsole would
> work and I'd be able to log this problem without
fiddling around with
> serial cables and other computers.

At first blush, I'm assuming this falls down because there
isn't a dhcp client 
built into the kernel. For nfs root, the dhcp client is
actually in the 
initrd, and I'm guessing netconsole wants to start up even
before the initrd 
has been unpacked.

-- 
Jarod Wilson
jwilsonredhat.com

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On Wednesday 16 April 2008 10:31:13 am John Summerfield
wrote:
> Jarod Wilson wrote:
> > On Wednesday 16 April 2008 05:55:32 am John
Summerfield wrote:
> >> I don't want to assign an IP address in the
kernel commandline, so it
> >> has to get one.
> >>
> >> At present, it doesn't do this, so netconsole
doesn't work.
> >>
> >> Just for the hell of it, I added
"ip=dhcp" as one does for nfs-root.
> >>
> >> Then, netconsole failed. After that, the
kernel used dhcp to get an IP
> >> address.
> >>
> >> Now, if the kernel could get the IP address
first, then netconsole would
> >> work and I'd be able to log this problem
without fiddling around with
> >> serial cables and other computers.
> >
> > At first blush, I'm assuming this falls down
because there isn't a dhcp
> > client built into the kernel. For nfs root, the
dhcp client is actually
> > in the initrd, and I'm guessing netconsole wants
to start up even before
> > the initrd has been unpacked.
>
> No, the kernel (if so built) doesn't require an initrd.
This worked as
> far back as 2.2, maybe earlier. It might once have only
done bootp, but
> it's had dhcp for years and years.

Sorry, I wasn't clear, I was speaking purely in the Red Hat
kernel case, where 
CONFIG_IP_PNP is not set. Of course, re-reading with the
context of me 
talking about new things that may be enabled in post-F9
rawhide, I'm guessing 
you were already aware of this, and were perhaps suggesting
that it be 
enabled as well...

-- 
Jarod Wilson
jwilsonredhat.com

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