Re: [Netconsole-devel] status?

[H. P. A. <hp...@tr...>]

Jim Garlick wrote:
> 
> Thanks,
> 
> I need to go read your archives, but I will toss out a few points that come
> to mind:
> 
> Sorry if my point#1 was confusing - I just want to be able to use this stuff
> over networks that are not necessarily IP, such as CAN (control area network
> used on the Meiko CS/2 for consoles), RS485, whatever.  Maybe I can make them
> look like UDP, but that sounds ugly.
> 

It's easy enough to replace UDP with any other datagram protocol, I'd
think.  It would require appropriate modifications, of course.

> 
> On the architecture, it seems to me like the netcon server approach creates
> a single point of failure where there doesn't need to be one.  The way
> I did the elan consoles was I made a range of elancon tty "callout devices"
> which can be virtually connected to the elancon tty console device on any
> node via an ioctl.  The client user-space software then just becomes minicom
> with support for some new tty ioctls (because the connected callout device
> looks just like /dev/ttyS0), and it is fully peer-to-peer.
> 

This sounds like an awful lot of complexity.especially for the client. 
The client really does need to be lean and mean.  To be utterly frank, a
solution of the complexity level you seem to advocate sounds like you
might as well go right ahead and just use ssh.

As far as supporting multiple servers, there is a lot you could do but it
would all come at considerable cost in client complexity.  Multicasting,
for example, requires that the client understands IGMP.  Unicasting to
multiple servers would require waiting for ACKs from all of them.

> 
> For logging, one could preserve this peer-to-peer architecture and implement
> a separate read-only connect for the logging daemon so it could concurrently
> capture console output while console sessions come and go.  Support for
> redundant logging servers could even be added.
> 

Let's think about what 

	-hpa


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