Mailing List Archive: Linux Virtual Server: Users

[lvs-users] Zero Active/Inactive connection

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himanshu.raina at naukri

Oct 27, 2010, 2:23 AM

Post #1 of 3 (510 views)
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[lvs-users] Zero Active/Inactive connection

Hi,

I observed a strange problem with one of my LVS servers today. The LVS
has multuple IP(s) configured of which
one of the interfaces eth0:5 had a problem. No requests were coming to
this interface of the box (I tested
this using tcpdump). The stats are given below

[root [at] linuxcp1019 ~]# ipvsadm -L -n --stats| grep -A4 192.168.2.5
TCP 192.168.2.5:80 0 0 0 0
0
-> host1:80 0 0 0 0 0
-> host2:80 0 0 0 0 0
-> host3:80 0 0 0 0 0
-> host4:80 0 0 0 0 0

[root [at] localhos ~]# ipvsadm -Ln --rate | grep -A4 192.168.2.5
TCP 192.168.2.5:80 0 0 0 0
0
-> host1:80 0 0 0 0 0
-> host2:80 0 0 0 0 0
-> host3:80 0 0 0 0 0
-> host4:80 0 0 0 0 0

I stopped and started ldirectord but it didn't improve the situation
whereas when I killed ldirectord and started
it, the problem got solved. What I'm unable to understand is how
different are the two methods when it comes to
re-initializing the daemon.

--
Regards,

Himanshu Raina
--
Did you hear about the model who sat on a broken bottle and cut a nice figure?
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graeme at graemef

Oct 27, 2010, 9:58 AM

Post #2 of 3 (496 views)
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Re: [lvs-users] Zero Active/Inactive connection [In reply to]

Hi

On Wed, 2010-10-27 at 14:53 +0530, Himanshu Raina wrote:
> I observed a strange problem with one of my LVS servers today. The LVS
> has multuple IP(s) configured of which
> one of the interfaces eth0:5 had a problem. No requests were coming to
> this interface of the box (I tested
> this using tcpdump). The stats are given below

This looks like the ARP problem to me. If no requests are hitting the
director, they're going somewhere else - probably one of the
realservers, directly.

Graeme

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Please read the documentation before posting - it's available at:
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graeme at graemef

Oct 29, 2010, 4:25 AM

Post #3 of 3 (467 views)
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Re: [lvs-users] Zero Active/Inactive connection [In reply to]

Hi

Your mail client is breaking the list address again... so I've cc'd the
list in response.

On Fri, 2010-10-29 at 13:07 +0530, Himanshu Raina wrote:
> Precisely, but my question is why would LVS mess only for one such
> domain. Also, why wouldn't a stop/start help in this case as opposed to
> kill/start. Also, when I checked the ARP table I didn't have any entry
> for the troubled IP or MAC. Moreover, if it is an ARP problem what is
> the work around and how does one solve such a problem.

Have you even looked at the comprehensive documentation which is linked
to in the footer of every single list message?

The ARP problem is a fundamental issue with LVS-DR, requiring that the
realservers are configured in such a way that they do not respond to ARP
requests for the VIP.

If they are not, then very unusual traffic characteristics can occur for
a given set of VIPs. Some will always go via the director, some will hop
around, and some will almost always "stick" to a realserver. It depends
entirely on local network configuration, devices, and network traffic
conditions.

Please - have a read. It's probably the single widest documented LVS
issue.

Graeme

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