Serial Port Concentrators vs. KVMs

Nicholas Henke henken at
Wed Apr 23 15:04:15 EDT 2003

On Wed, 2003-04-23 at 14:23, Gary Stiehr wrote:

> KVM Disadvantages
> -----------------
> * Lots of cables: Even if you do not use a mouse cable, you still have 
> two cables running from the back of each node.  I have heard of some 
> KVMs lately that use an adapter to combine all three kvm cables into 
> one.  I have not actually seen or used one but that would certainly help.

This get's to be a price issue too -- good KVM cables are darned

> * No remote access: The only KVM switches that I have seen with remote 
> access are "enterprise" KVM switches that have a high price tag.  I have 
> no experience with this type of KVM switch but I would imagine it would 
> be like a hybrid KVM/serial port concentrator.

> Serial Port Concentrator (SPC) Advantages
> -----------------------------------------
> * Remote access: Most SPCs that I looked at listed remote access as a 
> feature.  And some, including the Computone RAS2000 that I use, allow 
> you to access the them via ssh.

Best part -- never leave the comfort of your own desk :)

Generally Cheaper than KVM -- I am sure there is some knee point, but
for clusters in the >24 nodes size, remote serial is the way to go. You
will need some sort of KVM to access the nodes in the machine room, for
those problems where hardware is !#@$-ed, or if BIOS redirection is not
an option, as we have seen on some of our machines.

Also, when using a nice package like conserver ( (free :)),
you get logs of the console output -- absolutely critical for debugging
oops output -- unless you like transcribing oops to notepad, and then
back to a text file for ksymoops.

Nicholas Henke
Penguin Herder & Linux Cluster System Programmer
Liniac Project - Univ. of Pennsylvania

Beowulf mailing list, Beowulf at
To change your subscription (digest mode or unsubscribe) visit

More information about the Beowulf mailing list