Date: Fri, 23 Nov 2012 20:57:55 -0500 From: Paul Kraus <paul@kraus-haus.org> To: freebsd-questions@freebsd.org Subject: Re: Odd X11 over SSH issue Message-ID: <CALhcXPCh9twg4Kq4sYLT7RQTvLBOZ761h2Anq_cR16177%2B_-eQ@mail.gmail.com> In-Reply-To: <44obioatvk.fsf@lowell-desk.lan> References: <CALhcXPDSZ8Qgj4tG1UQdO7c4tB3cSJbW%2Bj0DDbpJFct2VZXs4g@mail.gmail.com> <44obioatvk.fsf@lowell-desk.lan>
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On Fri, Nov 23, 2012 at 4:31 PM, Lowell Gilbert
<freebsd-questions-local@be-well.ilk.org> wrote:
>> Observations:
>>
>> 1. When I first SSH into the box I see a long delay after the SSH
>> tunnel is setup before being prompted for a password, and I do not
>> know if this delay is related to the VBox issue. Details below.
>
> Running the ssh server with more debugging will probably tell you what's
> happening in this area.
Yup, I just have not had a chance to chase that one down, and
given that it happens once per SSH session, has not been a high
priority. I mentioned it in the spirit of full disclosure.
>> I would chock it up to network slowness, but I
>> do not see the same behavior with Firefox, xload, or xclock.
>
> That's not a fair comparison, because tunneling a whole X server
> involves passing a lot more events than tunneling an application to run
> on your local server. This is particularly painful because the X
> protocols are highly serial.
The VIrtualBox GUI (not the underlying VM console) should be
comparable to Firefox in terms of network load. Yes, xclock and xload
are much lower overhead as they are simpler apps. The difference
between Firefox (measured at under 10 seconds to open the window) and
VirtualBox (measured at 157 seconds to open the window) indicates that
_something_ is wrong.
Sorry if I was unclear. I am running 3 different VMs on this
server (soon to be more :-). One is WIn 2008 server as an RDP host for
a specific application, the others ar FreeBSD VMs, one for DNS and
DHCP, and the other for email / webmail. I manage the underlying Win
2008 instance via RDP (and that is how the end users connect), the two
FreeBSD VMs do not run a window manager at all and they are managed
via SSH connections. I use the VBoxHeadless executable to run the VMs
for production use. Normally I make config changes with the command
line tool VBoxManage, but in this case I had a FreeBSD VM that was not
booting so I needed the console (and to make various changes to the
config).
It is running the VBox management GUI on the physical layer server
that I am having fits with.
> Is there any particular reason you don't let the X server run remotely
> and attach to it with something more latency-friendly, like vnc? I would
> expect that to work vastly better on any OS, just because you get X
> (specifically, its tendency to head-of-line blocking) out of its own way.
The short answer to why X11 via SSH and not VNC for the management
is that I have not found a very clean way to have the VNC service
running for root without manual intervention to start it. Yes, I know
I could script it, but that adds one additional layer that needs to be
supported.
P.S. I did get my VM repaired, very slowly and painfully, but I still
need to track down the VBox GUI issue.
--
{--------1---------2---------3---------4---------5---------6---------7---------}
Paul Kraus
-> Principal Consultant, Business Information Technology Systems
-> Deputy Technical Director, LoneStarCon 3 (http://lonestarcon3.org/)
-> Sound Coordinator, Schenectady Light Opera Company (
http://www.sloctheater.org/ )
-> Technical Advisor, Troy Civic Theatre Company
-> Technical Advisor, RPI Players
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