Re: Newbie: LVS-DR on 2.4.3

To: lvs-users@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re: Newbie: LVS-DR on 2.4.3
Cc: scott@xxxxxxxxxxxxxxxxxx
From: Joseph Mack <mack.joseph@xxxxxxx>
Date: Wed, 25 Apr 2001 14:51:46 -0400
Scott Jones wrote:
> Hi Everybody,
> So, I'm trying to get LVS-DR set up on three boxes (on director and 2 real
> servers) for http (and later https).  I'm trying to get telnet working too
> since it seems to be the most simple to get working.  At this point, I have
> been able to get the director's kernel compiled with the ipvs patch, and I
> have run the configure perl script (I had to download perl-Net-DNS).
> To get the rc.lvs_dr script to run without "fatal" errors on the director
> box, I had to install fping and ntp.

hmm. I'd better fix that. If you're running configure-lvs-0.8, it will
test your ping to see if it can be run with the -c 1 option. 

Can your ping be run with

ping -c 1 machine_name(or IP)

If it can't then you'll either need a newer ping or fping. The output
from the rc.lvs file should show you what's going on here.

ntp is something I put in to keep all machines synchronised. 
ntpd is not neccessary for the LVS. I didn't realise
that the script would fail without it. Sorry about that.

> I get a message that $router_forwards
> is not set to Y|N (and that I'll be told which one to set it to when I run
> rc.lvs_dr on the real servers.  When I run it on my real servers, I don't
> get told which one to use...

Hmm. It looks like I was too cryptic here. The instructions
tell you to look if the director can ping the VIP. You then
get a table of what to do next. I'll look into this.

 > To deal with the "ARP problem" (which I don't really understand beyond the
> fact that the real servers need to NOT respond to packets sent to the VIP,
> unless they've been forwarded to the real server by the director -- is that
> a decent approximation of the problem?),

that's it, you've got it. 

> I have installed an extra NIC in
> each real server (they now have 3 apiece, and the VIP has been set up on
> eth2), as suggested as a potential solution on the HOWTO
> (
> When I run the rc.lvs_dr script on the real servers, I get:
> Warning:
> You are moving the VIP from one device
> (presumably from a previous LVS installation),
> to a different ethernet device.
> (even though in my lvs_dr.conf I have the SERVER_VIP_DEVICE set to eth2).

haven't tested this script with multiple NICs on the real-servers. 

> Then, it takes down my eth2 (so that ifconfig doesn't display eth2 anymore).

It's supposed to bring the VIP back up again. Obviously it hasn't. 
The script has been tested only with the VIP for VS-DR on an lo alias eg lo:0. 

> The wierdest thing is that after running rc.lvs_dr on both real servers, and
> sending an http request (or begin a telnet session) to the VIP, I actually
> get a response from ONLY ONE of the servers (and ipvsadm doesn't display any
> connection information for either http or telnet). 

Presumably the real-server is giving out arp replies for the VIP. On the
client, ping the VIP and then look at the MAC address associated with the VIP
by doing arp -a. In your setup the MAC address will (incorrectly) 
be on the real-server.

> It also doesn't seem to
> matter whether I have the VIP up or not on the real server...

hmm, not sure about this one. Let's leave it till last. I expect it
will clear up with the other problems.
> Does anyone have any suggestions for me?  I think that I going for pretty
> much the most basic configuration possible (but if anybody has any alternate
> suggestions, that'd be great!).

How about you put the SERVER_VIP_DEVICE to lo:0 until I get my script
fixed. If you're running a 2.2.x real-server, the script will handle
the arp problem for you. If you're running a 2.4.x real-server you'll
have to patch the real-server kernel before running the rc.lvs script. 
See the link at the bottom of this section.


Joseph Mack PhD, Senior Systems Engineer, Lockheed Martin
contractor to the National Environmental Supercomputer Center, 
mailto:mack.joseph@xxxxxxx ph# 919-541-0007, RTP, NC, USA

<Prev in Thread] Current Thread [Next in Thread>