cfowler at outpostsentinel
Dec 7, 2011, 7:25 AM
Post #6 of 7
On Wed, 2011-12-07 at 08:58 -0600, Joe Greco wrote:
> [from a message exchange in private e-mail]
> Right. I had a complex question. You suggested to me in private e-mail
Darn, my Android did not do a reply-all I thought I had provided a
suggestion to the list. Sorry about that. I was laying in the bed at
the time I responded. Unfortunately I was trying to go to sleep. :)
> > I have expanded my guest usage by using Rackspace and I expect to grow
> > into using them a lot more. They do not support any form of headless
> > monitoring.
> I never understood why these places can't be bothered to provide some form
> of headless monitoring.
> > "Both of THOSE problems would be solved if there was a
> > well-integrated feature in conserver to listen for connections."
> > Years ago I considered myself a "UNIX guru". I thought I knew
> > everything there was about UNIX. I thought I was a UNIX administrator.
> > I was naive. When I purchased "Advanced Programming in the UNIX
> > Environment", read it, and then starting coding. That is when I learned
> > UNIX. I guess it was when I was able to really start telling UNIX what
> > to do instead of it telling me what to do.
> Well, that there's the question. I'm looking to arrange the most elegant
> solution, rather than cobbling together something that's a botch. Given
> that conserver *already* has the capability of dealing with physical serial
> ports and remote network ports, which means that it has file descriptors
> for each port, the missing bits are probably some scaffolding for coping
> with a listening socket when there's not an established connection.
> > If you were to go down the path of making work what you have instead of
> > modification of VMware and conserver then I would write a program on the
> > host that runs conserver that listens for connections.
> I believe I actually said: "I suppose another option is to write a smarter
> version of netcat that does not act stupid. It's trivial to do, but
> watching nc processes stack up in an unexpected manner just suggested to
> me that maybe this was the wrong way to go about it."
> It's a fifteen minute program, but it means that there would be lots of
> extra processes and so as a solution it is really not that great. That's
> what prompted me to write to the mailing list. It seemed odd that no one
> else has thought of this.
> > I've not thought
> > about your problem in detail so what I suggest may not solve it.
> > Configure conserver to connect to pseudo ttys on the host. Those ttys
> > are created by the process that listens and marries the pseudos to the
> > remote device. I've done this many times when I've written serial tcp
> > code and RFC2217 type stuff.
> That's ugly and more complicated because you've just added another layer of
> complexity with a pty layer. I'm trying to go the other direction, getting
> rid of extra processes entirely and just see if conserver can be made to take
> care of it directly.
> > Administrators don't like to program because programming is boring and
> > the task of CS grads. No son, programming allows you to be the boss of
> > your systems not a slave. You don't like what your server is doing.
> > Tell it how to do it better. I'm not a CS grad. I'm an administrator
> > that has followed the path of a Jedi.
> No, coding is the task of CS grads. Administrators like to be lazy. I find
> the best path to being lazy is to come to a full understanding of the problem
> I want to solve, then find the most elegant and simple solution to fix it,
> then spend a little time coding it, at which point I have been completely
> successful at being lazy because now I never have to worry about whatever I
> just fixed again. CS grads can't and don't do this because they've been
> taught to code, and don't have the experience and insight to be able to
> understand systems as a whole. Understanding the bigger picture is the key
> to making the big bucks. :-)
I was never really taught. I taught myself. It was something to do
when we had PCs that did nothing without writing something. I'm not
very old, but lucky I grew up in the days of DOS. Not many distractions
in that OS (Internet) that kept a kid from wanting to write something.
Whenever I have a problem where I can't change what I'm working with I
enjoy finding external means of making it do what I want it to do.
Coding is one tool of doing that.
I should have said that coding is an option but should be a last resort.
I tend to use it as a last resort myself for stuff like this.
> > I have another problem with VMware that I can't fix since I don't have
> > the VM code. VMware does not respect tty settings in the guest and
> > apply those on the host. Not only do I have a serial port in my server
> > I also have an 8 port modem board. VMware treats these ports as raw
> > with no flow control. When old ascii devices dial in and dump alarms I
> > miss data when the software is too busy doing stuff to listen that ms
> > for incoming data. My solution is to remove that part of the software
> > out of the guest and run it on the host directly. Another solution is
> > to go real hardware with that piece. It may be possible to write code
> > on the host that loops and sets the termios settings on that tty. I've
> > not tried that.
> That sounds unfortunate. Getting serial right with virtualization is kind
> of stinky. I know we've had pretty good luck using Digi PortServers with
> their Windows "RealPort Driver" software which does a very admirable job
> of making the terminal server's port appear to be a directly connected serial
> port. Not technically a "virtualization" solution but works fine when
> virtualized, even on things like free ESXi, because it doesn't involve VMware
> at all - it's all network.
This is one solution I'm looking at too. Linux does support RFC2217
servers, but I'm not having a lot of luck finding clients. The way you
implement RFC2217 in client form requires an OS driver to create real
character devices. This is where serial->tcp type programs (which run
only in user space) suck. I know very little about Win32 internals so
in Windows it may be possible to implement character devices in user
land. On Linux the only character device you can implement is a pseudo
and many programs are hard coded to check for pseudo.
> You might find that something like that, combined with a USR MP/8, might make
> an acceptable replacement for your 8-port modem board. I think we got rid of
> our last MP/8 or I'd offer it to you.
> > The good news is that all of us here know how nice it is to work from
> > home, office, etc and not go to a data center. So many other folks look
> > at crash carts as a viable solution. The only time I ever go to our
> > rack is when I have to touch hardware. I can control power and get to
> > the console without leaving the comforts of my man cave at home.
> Crash carts are so 1995. You can't even *do* (much) stuff from the console
> of most VM hosts.
Yep. If I do go to the DC for my VM I use a browser on my netbook. I
still run my server headless.
> I've watched what used to be a roomful of gear back in the '90's shrink
> down to fit comfortably on two fairly lean VMware hosts. Our core
> support infrastructure, administrative servers, log analyzers, VPN servers,
> DHCP/TFTP servers, and all sorts of other miscellaneous stuff, has never
> been really that resource-intensive, and we've managed to cram 30 or 40
> different servers onto two hosts that idle at about 60 watts, around 100
> full tilt. Still need SAN and network gear, but reducing a 30 amp rack
> down to about 4 is pretty cool.
> But you have to be in your man cave? Dude, I can control my network from
> my *phone*. ;-) ;-)
Don't have to be. I like being here. I can do it on the road. :)
> How times have changed, eh.
I'm glad you are having success with going virtual. I've not done a lot
with it, but see it as a way for my org to add capability without adding
Some of my code is pretty intensive. I've seen one guest slow down
others. I think that may just be an issue with my hardware not being
good enough. With the VMware you are running do you have the ability
to control the amount of CPU (not number) that a guest can consume?
I'm a CLI guy so I love headless operation.
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