While VNC is good enough, it doesnt work
if the NIC is down. So is there a way to switch
amongst guest VMs once a crash carts
monitor/keyboard/mouse is attached to the
video/USB/etc. ports (on the back of the physical
box running XEN)?
For the network down (out-of-band)
emergencies, is there a way to
switch amongst domain and/or guest VM
consoles once a crash cart terminal (i.e.
terminal emulator, hyperterm, etc.) is
attached to the (primary) serial port
on the back (of a physical box running XEN)?
I see that any given VM can be configured
to map the VM console to the physical serial
port I/O but that would only work for one of the
VMs at a time
right?
Thanks,
Jadean
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While VNC/xvncd is usually good enough, it
doesn''t work if the NIC is down. So is there a
way to switch amongst guest VM''s once a crash cart''s
monitor/keyboard/mouse is attached to the
video/USB/etc. ports (on the back of the physical
box running XEN)?
For the network down (out-of-band)
emergencies, is there a way to
switch amongst domain and/or guest VM
consoles once a crash cart ''terminal'' (i.e.
terminal emulator, hyperterm, etc.) is
attached to the (primary) serial port
on the back (of a physical box running XEN)?
I see that any given VM can be configured
to map the VM /dev/ttyS0 (console) to the physical
serial port - but that would only work for one
of the VMs at a time ... right? I''m wondering
if there is some ''hot key sequence'' (e.g. +++,
^]) that would enable somebody to switch
between the various, VM-specific serial ports
(while attached to the physical serial port)?
Thanks, Steffen.
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> -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com]On Behalf Of Steffen > Hulegaard > Sent: Tuesday, March 06, 2007 12:00 PM > To: xen-users@lists.xensource.com > Subject: [Xen-users] Does XEN support crash carts? > > > While VNC is good enough, it doesn''t work > if the NIC is down. So is there a way to switch > amongst guest VM''s once a crash cart''s > monitor/keyboard/mouse is attached to the > video/USB/etc. ports (on the back of the physical > box running XEN)?I''m kind of a newbie to Xen, but can''t you just log into the Dom0 host - the physical box running Xen - through the serial port, or the crash cart KVM, and then connect to the DomU guest consoles using ''xm console DOMAIN''? -- Timothy W. Foreman ~ Security Administrator ~ tforeman@ibsys.com (651) 365-4181 ~ Internet Broadcasting ~ www.ibsys.com -- The Onion: Have you decided what you want to be when you grow up? Berkeley Breathed: Dad. The rest is frosting. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
This is what I do. On Mar 7, 2007, at 1:26 PM, Foreman, Tim wrote:> I''m kind of a newbie to Xen, but can''t you just log into > the Dom0 host - the physical box running Xen - through the serial > port, or the crash cart KVM, and then connect to the DomU guest > consoles using ''xm console DOMAIN''? > > -- > Timothy W. Foreman ~ Security Administrator ~ tforeman@ibsys.com > (651) 365-4181 ~ Internet Broadcasting ~ www.ibsys.com > -- > The Onion: Have you decided what you want to be when you grow up? > Berkeley Breathed: Dad. The rest is frosting.-- Jayson Vantuyl Systems Architect Engine Yard jvantuyl@engineyard.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Clearly, I''m a newbie. Thanks for the tip
on crash cart support (via ''xm console'').
It really helped - but I''m left with a nagging
(newbie) KVM question. I''d also love to confirm
my newfound serial-port understanding.
I now see how to configure support for
the physical serial port (i.e. see section 2.5.2 at
http://tx.downloads.xensource.com/downloads/docs/user/).
It seems easy enough to ''switch'' between
domains/guests using the escape character
mentioned. Once the serial connection is set/switched
to be talking to domain0, I can see using a
''xm consoles'' - or ''xm lists'' - command to
discover/choose active domain IDs. So everything
looks
fine via the crash cart''s null modem cable (to/from
the physical serial port). Right?
Much goodness ;-) Is there anything missing?
Maybe a listing of archived/saved VM images?
I just cannot seem to get my head around what
is happening on the physical VGA/USB ports.
What happens to these when one issues an ''xm console''
command (in/to Domain0)?
I wonder. As the serial--dev/console/--dev/ttyS0
of each domain gets ''switched'', is the
monitor--virtual-framebuffer association *also*
getting switched onto/off-of the physical VGA port?
Are the virtual keyboards/mice of each domain
*switched* - right along with the serial-port/console
and the virtual framebuffer? If so ... well then ...
more goodness ;-)
I really appreciate the clarification. I
apologize for being such a newbie :-( I''ve heard
some claims about there being some sort of
XEN limitation/deficiency here (and I''ve got
some limitations on what I can presently just try
myself). At any rate, the premise that XEN v3.x
lacks any ''crash cart'' support sounds like a myth.
Maybe this is just an out-of-date notion.
Thanks for all the help.
--- Jayson Vantuyl <jvantuyl@engineyard.com> wrote:
> This is what I do.
>
> On Mar 7, 2007, at 1:26 PM, Foreman, Tim wrote:
>
> > I''m kind of a newbie to Xen, but can''t you just
> log into
> > the Dom0 host - the physical box running Xen -
> through the serial
> > port, or the crash cart KVM, and then connect to
> the DomU guest
> > consoles using ''xm console DOMAIN''?
> >
> > --
> > Timothy W. Foreman ~ Security Administrator ~
> tforeman@ibsys.com
> > (651) 365-4181 ~ Internet Broadcasting ~
> www.ibsys.com
> > --
> > The Onion: Have you decided what you want to be
> when you grow up?
> > Berkeley Breathed: Dad. The rest is frosting.
>
> --
> Jayson Vantuyl
> Systems Architect
> Engine Yard
> jvantuyl@engineyard.com
>
>
>
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Kraska, Joe A \(US SSA\)
2007-Mar-08 16:25 UTC
RE: [Xen-users] Does XEN support crash carts?
> I just cannot seem to get my head around what > is happening on the physical VGA/USB ports. > What happens to these when one issues an ''xm console'' > command (in/to Domain0)?While I cannot answer the question as to "what happens," I can say that you definitely don''t want to try to attach to the same console twice. :) Joe. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> Clearly, I''m a newbie. Thanks for the tip > on crash cart support (via ''xm console''). > It really helped - but I''m left with a nagging > (newbie) KVM question. I''d also love to confirm > my newfound serial-port understanding. > > I now see how to configure support for > the physical serial port (i.e. see section 2.5.2 at > http://tx.downloads.xensource.com/downloads/docs/user/).Cool.> It seems easy enough to ''switch'' between > domains/guests using the escape character > mentioned. Once the serial connection is set/switched > to be talking to domain0, I can see using a > ''xm consoles'' - or ''xm lists'' - command to > discover/choose active domain IDs. So everything > looks > fine via the crash cart''s null modem cable (to/from > the physical serial port). Right?Right.> Much goodness ;-) Is there anything missing? > Maybe a listing of archived/saved VM images?I''m not entirely clear what you mean here... If you''re using Xend''s lifecycle management you can list all domains it knows about (that is, including ones that are currently not running / suspended). If you''re not (i.e. just using config files) then you can only get information on the currently running domains. ISTR the lifecycle management stuff is still a "preview" not officially finished but I could be wrong here. Does this answer your question?> I just cannot seem to get my head around what > is happening on the physical VGA/USB ports. > What happens to these when one issues an ''xm console'' > command (in/to Domain0)? > > I wonder. As the serial--dev/console/--dev/ttyS0 > of each domain gets ''switched'', is the > monitor--virtual-framebuffer association *also* > getting switched onto/off-of the physical VGA port? > Are the virtual keyboards/mice of each domain > *switched* - right along with the serial-port/console > and the virtual framebuffer? If so ... well then ... > more goodness ;-) >xm console doesn''t actually switch ownership of the console port, it''s just a program that connects to a guest''s virtual serial port and blats out data to a terminal. It works just the same if you''re using dom0''s serial port, or dom0''s VGA console, or logged into dom0 over ssh. dom0 retains ownership of the serial port, VGA, USB and almost all the other hardware at all times (unless you explicitly give control of some PCI device to a guest). When you are talking directly to the IO devices on the host system, you''re talking to dom0. If you want to get to a guest''s framebuffer / keyboard, you can access it via dom0 - for instance by having domain 0 export it over the network using VNC.> I really appreciate the clarification. I > apologize for being such a newbie :-( I''ve heard > some claims about there being some sort of > XEN limitation/deficiency here (and I''ve got > some limitations on what I can presently just try > myself). At any rate, the premise that XEN v3.x > lacks any ''crash cart'' support sounds like a myth. > Maybe this is just an out-of-date notion.Think of dom0 as being a combination of these things: * IP KVM for the running domUs (can relay their framebuffer and mouse / keyboard over the network) * serial console concentrator for the domUs (can relay their serial console over ssh / whatever - just log in to dom0 and run xm console) * management module for all the domUs (can shut them down (politely, or not), reboot them, etc without requiring login to the domU itself). It can also core dump crashing domUs for later analysis, I believe. dom0 is effectively like a software implementation of a sophisticated management card, or like the hypervisor console found on IBM mainframes. It just happens to also be a Linux environment. You just need to be able to access dom0 over the network to do all these things; otherwise, log into dom0 with your crash cart and you can do this stuff using that instead. Does that help clarify things a bit? The ability to do this sort of stuff is one of the big wins of virtual machine technology on servers - (Xen''s competitors tend to offer this type of functionality too). Don''t hesistate to ask if you have any more questions. Cheers, Mark PS. another "management processor"-like feature is a software watchdog device which runs *outside* of the virtual machine so that no amount of corruption of the domU kernel can cause it to fail. I''m working on this at the moment, and hoping to get it in to the 3.0.6 release at latest.> Thanks for all the help. > > --- Jayson Vantuyl <jvantuyl@engineyard.com> wrote: > > This is what I do. > > > > On Mar 7, 2007, at 1:26 PM, Foreman, Tim wrote: > > > I''m kind of a newbie to Xen, but can''t you just > > > > log into > > > > > the Dom0 host - the physical box running Xen - > > > > through the serial > > > > > port, or the crash cart KVM, and then connect to > > > > the DomU guest > > > > > consoles using ''xm console DOMAIN''? > > > > > > -- > > > Timothy W. Foreman ~ Security Administrator ~ > > > > tforeman@ibsys.com > > > > > (651) 365-4181 ~ Internet Broadcasting ~ > > > > www.ibsys.com > > > > > -- > > > The Onion: Have you decided what you want to be > > > > when you grow up? > > > > > Berkeley Breathed: Dad. The rest is frosting. > > > > -- > > Jayson Vantuyl > > Systems Architect > > Engine Yard > > jvantuyl@engineyard.com > > ___________________________________________________________________________ >_________ Looking for earth-friendly autos? > Browse Top Cars by "Green Rating" at Yahoo! Autos'' Green Center. > http://autos.yahoo.com/green_center/ > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users-- Dave: Just a question. What use is a unicyle with no seat? And no pedals! Mark: To answer a question with a question: What use is a skateboard? Dave: Skateboards have wheels. Mark: My wheel has a wheel! _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Awesome answers! The XEN community rocks!
It now seems as if there is shred of truth
to the ''myth''. Still, XEN already has almost
everything anyone might want - so I''m thinking of
ways I might contribute to fix what I''m thinking
might be a *very* smallish XEN limitation. Please
bear with me. I''ll attempt to explain.
Recall from the beginning of this
thread that I mentioned that VNC is almost
always good enough. I was bringing up the
very rare ''crash cart'' case. For instance,
a NIC card might be down/dysfunctional.
Even with a down NIC, the null modem (cross-over)
cable to the physical serial port works
(as explained - Dom0 mediates/relays the chosen
DomU serial traffic, etc.). However ... unless
I misunderstand something about VNC, VNC is
*NOT* going to work with a down NIC. If I
recall correctly, VNC requires a TCP/IP
connection. Of course, I''m newbie ignorant
of any special features tha might have been
added to XvncD. Am I spouting nonsense here?
So, in the glorious ignorance of a newbie,
I''m guessing that the physical VGA/USB ports
are not ''active'' (on the back of the box).
Any attempt to cable up a crash cart LCD/monitor,
keyboard and/or mouse, to these inactive
physical ports, will not work. Right? Or
did I miss something major?
I''d really appreciate knowing if I''m
just all muddled here. If I''m right, then
I suspect that this is the genesis of the
nit that I''ve heard picked with XEN.
If this is a *tiny* XEN nit, then I''m very
tempted to see what might be done to fix it.
Since this is such a once-in-a-blue-moon nit,
I''m thinking perhaps nobody else has bothered
with it. Obviously, this isn''t a huge
priority (because VNC is *almost* always good
enough). All the same, this sounds like a
potentially fun project (albeit a project
whose scope might be surprising - depending on
many things that I presently know very, very
little about ;-).
Thanks again,
--- Mark Williamson <mark.williamson@cl.cam.ac.uk>
wrote:
> > Clearly, I''m a newbie. Thanks for the tip
> > on crash cart support (via ''xm console'').
> > It really helped - but I''m left with a nagging
> > (newbie) KVM question. I''d also love to confirm
> > my newfound serial-port understanding.
> >
> > I now see how to configure support for
> > the physical serial port (i.e. see section 2.5.2
> at
> >
>
http://tx.downloads.xensource.com/downloads/docs/user/).>
> Cool.
>
> > It seems easy enough to ''switch'' between
> > domains/guests using the escape character
> > mentioned. Once the serial connection is
> set/switched
> > to be talking to domain0, I can see using a
> > ''xm consoles'' - or ''xm lists'' -
command to
> > discover/choose active domain IDs. So everything
> > looks
> > fine via the crash cart''s null modem cable
> (to/from
> > the physical serial port). Right?
>
> Right.
>
> > Much goodness ;-) Is there anything missing?
> > Maybe a listing of archived/saved VM images?
>
> I''m not entirely clear what you mean here...
>
> If you''re using Xend''s lifecycle management you can
> list all domains it knows
> about (that is, including ones that are currently
> not running / suspended).
> If you''re not (i.e. just using config files) then
> you can only get
> information on the currently running domains. ISTR
> the lifecycle management
> stuff is still a "preview" not officially finished
> but I could be wrong here.
>
> Does this answer your question?
>
> > I just cannot seem to get my head around what
> > is happening on the physical VGA/USB ports.
> > What happens to these when one issues an ''xm
> console''
> > command (in/to Domain0)?
> >
> > I wonder. As the
> serial--dev/console/--dev/ttyS0
> > of each domain gets ''switched'', is the
> > monitor--virtual-framebuffer association *also*
> > getting switched onto/off-of the physical VGA
> port?
> > Are the virtual keyboards/mice of each domain
> > *switched* - right along with the
> serial-port/console
> > and the virtual framebuffer? If so ... well then
> ...
> > more goodness ;-)
> >
>
> xm console doesn''t actually switch ownership of the
> console port, it''s just a
> program that connects to a guest''s virtual serial
> port and blats out data to
> a terminal. It works just the same if you''re using
> dom0''s serial port, or
> dom0''s VGA console, or logged into dom0 over ssh.
>
> dom0 retains ownership of the serial port, VGA, USB
> and almost all the other
> hardware at all times (unless you explicitly give
> control of some PCI device
> to a guest).
>
> When you are talking directly to the IO devices on
> the host system, you''re
> talking to dom0. If you want to get to a guest''s
> framebuffer / keyboard, you
> can access it via dom0 - for instance by having
> domain 0 export it over the
> network using VNC.
>
> > I really appreciate the clarification. I
> > apologize for being such a newbie :-( I''ve heard
> > some claims about there being some sort of
> > XEN limitation/deficiency here (and I''ve got
> > some limitations on what I can presently just try
> > myself). At any rate, the premise that XEN v3.x
> > lacks any ''crash cart'' support sounds like a myth.
> > Maybe this is just an out-of-date notion.
>
> Think of dom0 as being a combination of these
> things:
> * IP KVM for the running domUs (can relay their
> framebuffer and mouse /
> keyboard over the network)
> * serial console concentrator for the domUs (can
> relay their serial console
> over ssh / whatever - just log in to dom0 and run xm
> console)
> * management module for all the domUs (can shut them
> down (politely, or not),
> reboot them, etc without requiring login to the domU
> itself). It can also
> core dump crashing domUs for later analysis, I
> believe.
>
> dom0 is effectively like a software implementation
> of a sophisticated
> management card, or like the hypervisor console
> found on IBM mainframes. It
> just happens to also be a Linux environment. You
> just need to be able to
> access dom0 over the network to do all these things;
> otherwise, log into dom0
> with your crash cart and you can do this stuff using
> that instead.
>
> Does that help clarify things a bit? The ability to
> do this sort of stuff is
> one of the big wins of virtual machine technology on
> servers - (Xen''s
> competitors tend to offer this type of functionality
> too).
>
> Don''t hesistate to ask if you have any more
> questions.
>
> Cheers,
> Mark
>
> PS. another "management processor"-like feature is a
> software watchdog device
> which runs *outside* of the virtual machine so that
> no amount of corruption
> of the domU kernel can cause it to fail. I''m
> working on this at the moment,
> and hoping to get it in to the 3.0.6 release at
> latest.
>
> > Thanks for all the help.
> >
> > --- Jayson Vantuyl <jvantuyl@engineyard.com>
> wrote:
> > > This is what I do.
> > >
> > > On Mar 7, 2007, at 1:26 PM, Foreman, Tim wrote:
> > > > I''m kind of a newbie to Xen, but can''t you
> just
> > >
> > > log into
> > >
> > > > the Dom0 host - the physical box running Xen -
> > >
> > > through the serial
> > >
> > > > port, or the crash cart KVM, and then connect
> to
> > >
> > > the DomU guest
> > >
> > > > consoles using ''xm console DOMAIN''?
> > > >
> > > > --
> > > > Timothy W. Foreman ~ Security Administrator ~
> > >
> > > tforeman@ibsys.com
> > >
> > > > (651) 365-4181 ~ Internet Broadcasting ~
> > >
> > > www.ibsys.com
> > >
> > > > --
> > > > The Onion: Have you decided what you want to
> be
> > >
> > > when you grow up?
> > >
> > > > Berkeley Breathed: Dad. The rest is frosting.
> > >
> > > --
> > > Jayson Vantuyl
> > > Systems Architect
> > > Engine Yard
> > > jvantuyl@engineyard.com
> >
> >
>
___________________________________________________________________________> >_________ Looking for earth-friendly autos?
> > Browse Top Cars by "Green Rating" at Yahoo! Autos''
> Green Center.
> > http://autos.yahoo.com/green_center/
> >
> > _______________________________________________
> > Xen-users mailing list
>
=== message truncated ==
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> Awesome answers! The XEN community rocks! > > It now seems as if there is shred of truth > to the ''myth''. Still, XEN already has almost > everything anyone might want - so I''m thinking of > ways I might contribute to fix what I''m thinking > might be a *very* smallish XEN limitation. Please > bear with me. I''ll attempt to explain.OK, cool.> Recall from the beginning of this > thread that I mentioned that VNC is almost > always good enough. I was bringing up the > very rare ''crash cart'' case. For instance, > a NIC card might be down/dysfunctional. > Even with a down NIC, the null modem (cross-over) > cable to the physical serial port works > (as explained - Dom0 mediates/relays the chosen > DomU serial traffic, etc.). However ... unless > I misunderstand something about VNC, VNC is > *NOT* going to work with a down NIC. If I > recall correctly, VNC requires a TCP/IP > connection. Of course, I''m newbie ignorant > of any special features tha might have been > added to XvncD. Am I spouting nonsense here?No, you''re not. However, if you install a VNC viewer on dom0 then you could fire it up on dom0''s local console and get access to the domU framebuffer that way.> So, in the glorious ignorance of a newbie, > I''m guessing that the physical VGA/USB ports > are not ''active'' (on the back of the box). > Any attempt to cable up a crash cart LCD/monitor, > keyboard and/or mouse, to these inactive > physical ports, will not work. Right? Or > did I miss something major?They''ll work, you just can only get domain 0 talking to you. So you''ll have dom0''s VGA and USB connections; fire up the VNC viewer in dom0 and you''ll be set. Dom 0 is a full Linux in its own right, with access to all the hardware: just fire up an X server and it''ll come out on the VGA port. It''s normally the only domain privileged to do this, but you can use it to get to everything else. There''s also a local console client that doesn''t use any kind of networking, but VNC is nice because it easily extends to the networked case. Does that solve your problem? Cheers, Mark> I''d really appreciate knowing if I''m > just all muddled here. If I''m right, then > I suspect that this is the genesis of the > nit that I''ve heard picked with XEN. > > If this is a *tiny* XEN nit, then I''m very > tempted to see what might be done to fix it. > Since this is such a once-in-a-blue-moon nit, > I''m thinking perhaps nobody else has bothered > with it. Obviously, this isn''t a huge > priority (because VNC is *almost* always good > enough). All the same, this sounds like a > potentially fun project (albeit a project > whose scope might be surprising - depending on > many things that I presently know very, very > little about ;-). > > Thanks again, > > > --- Mark Williamson <mark.williamson@cl.cam.ac.uk> > > wrote: > > > Clearly, I''m a newbie. Thanks for the tip > > > on crash cart support (via ''xm console''). > > > It really helped - but I''m left with a nagging > > > (newbie) KVM question. I''d also love to confirm > > > my newfound serial-port understanding. > > > > > > I now see how to configure support for > > > the physical serial port (i.e. see section 2.5.2 > > > > at > > http://tx.downloads.xensource.com/downloads/docs/user/). > > > Cool. > > > > > It seems easy enough to ''switch'' between > > > domains/guests using the escape character > > > mentioned. Once the serial connection is > > > > set/switched > > > > > to be talking to domain0, I can see using a > > > ''xm consoles'' - or ''xm lists'' - command to > > > discover/choose active domain IDs. So everything > > > looks > > > fine via the crash cart''s null modem cable > > > > (to/from > > > > > the physical serial port). Right? > > > > Right. > > > > > Much goodness ;-) Is there anything missing? > > > Maybe a listing of archived/saved VM images? > > > > I''m not entirely clear what you mean here... > > > > If you''re using Xend''s lifecycle management you can > > list all domains it knows > > about (that is, including ones that are currently > > not running / suspended). > > If you''re not (i.e. just using config files) then > > you can only get > > information on the currently running domains. ISTR > > the lifecycle management > > stuff is still a "preview" not officially finished > > but I could be wrong here. > > > > Does this answer your question? > > > > > I just cannot seem to get my head around what > > > is happening on the physical VGA/USB ports. > > > What happens to these when one issues an ''xm > > > > console'' > > > > > command (in/to Domain0)? > > > > > > I wonder. As the > > > > serial--dev/console/--dev/ttyS0 > > > > > of each domain gets ''switched'', is the > > > monitor--virtual-framebuffer association *also* > > > getting switched onto/off-of the physical VGA > > > > port? > > > > > Are the virtual keyboards/mice of each domain > > > *switched* - right along with the > > > > serial-port/console > > > > > and the virtual framebuffer? If so ... well then > > > > ... > > > > > more goodness ;-) > > > > xm console doesn''t actually switch ownership of the > > console port, it''s just a > > program that connects to a guest''s virtual serial > > port and blats out data to > > a terminal. It works just the same if you''re using > > dom0''s serial port, or > > dom0''s VGA console, or logged into dom0 over ssh. > > > > dom0 retains ownership of the serial port, VGA, USB > > and almost all the other > > hardware at all times (unless you explicitly give > > control of some PCI device > > to a guest). > > > > When you are talking directly to the IO devices on > > the host system, you''re > > talking to dom0. If you want to get to a guest''s > > framebuffer / keyboard, you > > can access it via dom0 - for instance by having > > domain 0 export it over the > > network using VNC. > > > > > I really appreciate the clarification. I > > > apologize for being such a newbie :-( I''ve heard > > > some claims about there being some sort of > > > XEN limitation/deficiency here (and I''ve got > > > some limitations on what I can presently just try > > > myself). At any rate, the premise that XEN v3.x > > > lacks any ''crash cart'' support sounds like a myth. > > > Maybe this is just an out-of-date notion. > > > > Think of dom0 as being a combination of these > > things: > > * IP KVM for the running domUs (can relay their > > framebuffer and mouse / > > keyboard over the network) > > * serial console concentrator for the domUs (can > > relay their serial console > > over ssh / whatever - just log in to dom0 and run xm > > console) > > * management module for all the domUs (can shut them > > down (politely, or not), > > reboot them, etc without requiring login to the domU > > itself). It can also > > core dump crashing domUs for later analysis, I > > believe. > > > > dom0 is effectively like a software implementation > > of a sophisticated > > management card, or like the hypervisor console > > found on IBM mainframes. It > > just happens to also be a Linux environment. You > > just need to be able to > > access dom0 over the network to do all these things; > > otherwise, log into dom0 > > with your crash cart and you can do this stuff using > > that instead. > > > > Does that help clarify things a bit? The ability to > > do this sort of stuff is > > one of the big wins of virtual machine technology on > > servers - (Xen''s > > competitors tend to offer this type of functionality > > too). > > > > Don''t hesistate to ask if you have any more > > questions. > > > > Cheers, > > Mark > > > > PS. another "management processor"-like feature is a > > software watchdog device > > which runs *outside* of the virtual machine so that > > no amount of corruption > > of the domU kernel can cause it to fail. I''m > > working on this at the moment, > > and hoping to get it in to the 3.0.6 release at > > latest. > > > > > Thanks for all the help. > > > > > > --- Jayson Vantuyl <jvantuyl@engineyard.com> > > > > wrote: > > > > This is what I do. > > > > > > > > On Mar 7, 2007, at 1:26 PM, Foreman, Tim wrote: > > > > > I''m kind of a newbie to Xen, but can''t you > > > > just > > > > > > log into > > > > > > > > > the Dom0 host - the physical box running Xen - > > > > > > > > through the serial > > > > > > > > > port, or the crash cart KVM, and then connect > > > > to > > > > > > the DomU guest > > > > > > > > > consoles using ''xm console DOMAIN''? > > > > > > > > > > -- > > > > > Timothy W. Foreman ~ Security Administrator ~ > > > > > > > > tforeman@ibsys.com > > > > > > > > > (651) 365-4181 ~ Internet Broadcasting ~ > > > > > > > > www.ibsys.com > > > > > > > > > -- > > > > > The Onion: Have you decided what you want to > > > > be > > > > > > when you grow up? > > > > > > > > > Berkeley Breathed: Dad. The rest is frosting. > > > > > > > > -- > > > > Jayson Vantuyl > > > > Systems Architect > > > > Engine Yard > > > > jvantuyl@engineyard.com > > ___________________________________________________________________________ > > > >_________ Looking for earth-friendly autos? > > > Browse Top Cars by "Green Rating" at Yahoo! Autos'' > > > > Green Center. > > > > > http://autos.yahoo.com/green_center/ > > > > > > _______________________________________________ > > > Xen-users mailing list > > === message truncated ==> > > > > ___________________________________________________________________________ >_________ Don''t get soaked. Take a quick peek at the forecast > with the Yahoo! Search weather shortcut. > http://tools.search.yahoo.com/shortcuts/#loc_weather-- Dave: Just a question. What use is a unicyle with no seat? And no pedals! Mark: To answer a question with a question: What use is a skateboard? Dave: Skateboards have wheels. Mark: My wheel has a wheel! _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> Recall from the beginning of this > thread that I mentioned that VNC is almost > always good enough. I was bringing up the > very rare ''crash cart'' case. For instance, > a NIC card might be down/dysfunctional. > Even with a down NIC, the null modem (cross-over) > cable to the physical serial port works > (as explained - Dom0 mediates/relays the chosen > DomU serial traffic, etc.). However ... unless > I misunderstand something about VNC, VNC is > *NOT* going to work with a down NIC. If I > recall correctly, VNC requires a TCP/IP > connection. Of course, I''m newbie ignorant > of any special features tha might have been > added to XvncD. Am I spouting nonsense here?Just thought I''d clarify here: it''s no longer the case (as of 3.0.4) that domains have to export their own displays using VNC. Dom0 can do it for them with no VNC configuration required in the guest. If you can get graphics out of dom0 somehow (over ssh, over VNC, from the VGA port) you should be able to get the framebuffers and serial ports of the guest OSes. Cheers, Mark> So, in the glorious ignorance of a newbie, > I''m guessing that the physical VGA/USB ports > are not ''active'' (on the back of the box). > Any attempt to cable up a crash cart LCD/monitor, > keyboard and/or mouse, to these inactive > physical ports, will not work. Right? Or > did I miss something major? > > I''d really appreciate knowing if I''m > just all muddled here. If I''m right, then > I suspect that this is the genesis of the > nit that I''ve heard picked with XEN. > > If this is a *tiny* XEN nit, then I''m very > tempted to see what might be done to fix it. > Since this is such a once-in-a-blue-moon nit, > I''m thinking perhaps nobody else has bothered > with it. Obviously, this isn''t a huge > priority (because VNC is *almost* always good > enough). All the same, this sounds like a > potentially fun project (albeit a project > whose scope might be surprising - depending on > many things that I presently know very, very > little about ;-). > > Thanks again, > > > --- Mark Williamson <mark.williamson@cl.cam.ac.uk> > > wrote: > > > Clearly, I''m a newbie. Thanks for the tip > > > on crash cart support (via ''xm console''). > > > It really helped - but I''m left with a nagging > > > (newbie) KVM question. I''d also love to confirm > > > my newfound serial-port understanding. > > > > > > I now see how to configure support for > > > the physical serial port (i.e. see section 2.5.2 > > > > at > > http://tx.downloads.xensource.com/downloads/docs/user/). > > > Cool. > > > > > It seems easy enough to ''switch'' between > > > domains/guests using the escape character > > > mentioned. Once the serial connection is > > > > set/switched > > > > > to be talking to domain0, I can see using a > > > ''xm consoles'' - or ''xm lists'' - command to > > > discover/choose active domain IDs. So everything > > > looks > > > fine via the crash cart''s null modem cable > > > > (to/from > > > > > the physical serial port). Right? > > > > Right. > > > > > Much goodness ;-) Is there anything missing? > > > Maybe a listing of archived/saved VM images? > > > > I''m not entirely clear what you mean here... > > > > If you''re using Xend''s lifecycle management you can > > list all domains it knows > > about (that is, including ones that are currently > > not running / suspended). > > If you''re not (i.e. just using config files) then > > you can only get > > information on the currently running domains. ISTR > > the lifecycle management > > stuff is still a "preview" not officially finished > > but I could be wrong here. > > > > Does this answer your question? > > > > > I just cannot seem to get my head around what > > > is happening on the physical VGA/USB ports. > > > What happens to these when one issues an ''xm > > > > console'' > > > > > command (in/to Domain0)? > > > > > > I wonder. As the > > > > serial--dev/console/--dev/ttyS0 > > > > > of each domain gets ''switched'', is the > > > monitor--virtual-framebuffer association *also* > > > getting switched onto/off-of the physical VGA > > > > port? > > > > > Are the virtual keyboards/mice of each domain > > > *switched* - right along with the > > > > serial-port/console > > > > > and the virtual framebuffer? If so ... well then > > > > ... > > > > > more goodness ;-) > > > > xm console doesn''t actually switch ownership of the > > console port, it''s just a > > program that connects to a guest''s virtual serial > > port and blats out data to > > a terminal. It works just the same if you''re using > > dom0''s serial port, or > > dom0''s VGA console, or logged into dom0 over ssh. > > > > dom0 retains ownership of the serial port, VGA, USB > > and almost all the other > > hardware at all times (unless you explicitly give > > control of some PCI device > > to a guest). > > > > When you are talking directly to the IO devices on > > the host system, you''re > > talking to dom0. If you want to get to a guest''s > > framebuffer / keyboard, you > > can access it via dom0 - for instance by having > > domain 0 export it over the > > network using VNC. > > > > > I really appreciate the clarification. I > > > apologize for being such a newbie :-( I''ve heard > > > some claims about there being some sort of > > > XEN limitation/deficiency here (and I''ve got > > > some limitations on what I can presently just try > > > myself). At any rate, the premise that XEN v3.x > > > lacks any ''crash cart'' support sounds like a myth. > > > Maybe this is just an out-of-date notion. > > > > Think of dom0 as being a combination of these > > things: > > * IP KVM for the running domUs (can relay their > > framebuffer and mouse / > > keyboard over the network) > > * serial console concentrator for the domUs (can > > relay their serial console > > over ssh / whatever - just log in to dom0 and run xm > > console) > > * management module for all the domUs (can shut them > > down (politely, or not), > > reboot them, etc without requiring login to the domU > > itself). It can also > > core dump crashing domUs for later analysis, I > > believe. > > > > dom0 is effectively like a software implementation > > of a sophisticated > > management card, or like the hypervisor console > > found on IBM mainframes. It > > just happens to also be a Linux environment. You > > just need to be able to > > access dom0 over the network to do all these things; > > otherwise, log into dom0 > > with your crash cart and you can do this stuff using > > that instead. > > > > Does that help clarify things a bit? The ability to > > do this sort of stuff is > > one of the big wins of virtual machine technology on > > servers - (Xen''s > > competitors tend to offer this type of functionality > > too). > > > > Don''t hesistate to ask if you have any more > > questions. > > > > Cheers, > > Mark > > > > PS. another "management processor"-like feature is a > > software watchdog device > > which runs *outside* of the virtual machine so that > > no amount of corruption > > of the domU kernel can cause it to fail. I''m > > working on this at the moment, > > and hoping to get it in to the 3.0.6 release at > > latest. > > > > > Thanks for all the help. > > > > > > --- Jayson Vantuyl <jvantuyl@engineyard.com> > > > > wrote: > > > > This is what I do. > > > > > > > > On Mar 7, 2007, at 1:26 PM, Foreman, Tim wrote: > > > > > I''m kind of a newbie to Xen, but can''t you > > > > just > > > > > > log into > > > > > > > > > the Dom0 host - the physical box running Xen - > > > > > > > > through the serial > > > > > > > > > port, or the crash cart KVM, and then connect > > > > to > > > > > > the DomU guest > > > > > > > > > consoles using ''xm console DOMAIN''? > > > > > > > > > > -- > > > > > Timothy W. Foreman ~ Security Administrator ~ > > > > > > > > tforeman@ibsys.com > > > > > > > > > (651) 365-4181 ~ Internet Broadcasting ~ > > > > > > > > www.ibsys.com > > > > > > > > > -- > > > > > The Onion: Have you decided what you want to > > > > be > > > > > > when you grow up? > > > > > > > > > Berkeley Breathed: Dad. The rest is frosting. > > > > > > > > -- > > > > Jayson Vantuyl > > > > Systems Architect > > > > Engine Yard > > > > jvantuyl@engineyard.com > > ___________________________________________________________________________ > > > >_________ Looking for earth-friendly autos? > > > Browse Top Cars by "Green Rating" at Yahoo! Autos'' > > > > Green Center. > > > > > http://autos.yahoo.com/green_center/ > > > > > > _______________________________________________ > > > Xen-users mailing list > > === message truncated ==> > > > > ___________________________________________________________________________ >_________ Don''t get soaked. Take a quick peek at the forecast > with the Yahoo! Search weather shortcut. > http://tools.search.yahoo.com/shortcuts/#loc_weather-- Dave: Just a question. What use is a unicyle with no seat? And no pedals! Mark: To answer a question with a question: What use is a skateboard? Dave: Skateboards have wheels. Mark: My wheel has a wheel! _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Mark Williamson wrote:>> Awesome answers! The XEN community rocks! >> >> It now seems as if there is shred of truth >> to the ''myth''. Still, XEN already has almost >> everything anyone might want - so I''m thinking of >> ways I might contribute to fix what I''m thinking >> might be a *very* smallish XEN limitation. Please >> bear with me. I''ll attempt to explain. > > OK, cool. > >> Recall from the beginning of this >> thread that I mentioned that VNC is almost >> always good enough. I was bringing up the >> very rare ''crash cart'' case. For instance, >> a NIC card might be down/dysfunctional. >> Even with a down NIC, the null modem (cross-over) >> cable to the physical serial port works >> (as explained - Dom0 mediates/relays the chosen >> DomU serial traffic, etc.). However ... unless >> I misunderstand something about VNC, VNC is >> *NOT* going to work with a down NIC. If I >> recall correctly, VNC requires a TCP/IP >> connection. Of course, I''m newbie ignorant >> of any special features tha might have been >> added to XvncD. Am I spouting nonsense here? > > No, you''re not. However, if you install a VNC viewer on dom0 then > you could fire it up on dom0''s local console and get access to the > domU framebuffer that way.You could also set up PPP to provide and route an alternate network path over a serial port. Me, I keep a spare USB/100baseT adapter around for just such moments to avoid being too off-line to get the drivers for a network card, or to help backup a machine due for hardware maintenance and unable to use the NIC for whatever reason.>> So, in the glorious ignorance of a newbie, >> I''m guessing that the physical VGA/USB ports >> are not ''active'' (on the back of the box). >> Any attempt to cable up a crash cart LCD/monitor, >> keyboard and/or mouse, to these inactive >> physical ports, will not work. Right? Or >> did I miss something major? > > They''ll work, you just can only get domain 0 talking to you. So > you''ll have dom0''s VGA and USB connections; fire up the VNC viewer in > dom0 and you''ll be set.With what I described, the USB port can provide a normal network access without using the NIC. You''ll have to reconfigure the DomU''s to use it, but it''s workable. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users