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Am Freitag, 23. Mai 2014, 10:44:10 schrieb Bryan K. Wright:
> Hi folks,
>
> I've been successfully using IPVS under CentOS 5 for a long
> time, and I've recently been using it with CentOS 6. Just this
> week I noticed a performance problem with the CentOS 6 cluster, though,
> and I'm wondering if anyone can offer advice on how to track it down.
>
> In both cases, the IPVS setup directs incoming ssh connections
> to one of several login nodes, something like this:
>
> TCP my.host.edu:ssh wlc
> -> host1.internal:ssh Masq 9 0 0
> -> host2.internal:ssh Masq 10 0 0
> -> host3.internal:ssh Masq 10 0 0
>
> On the CentOS 6 cluster, I noticed that X applications like emacs
> were taking a long time to open, and were very laggy. The CentOS 5
> cluster doesn't act this way at all.
>
> I did some experiments, and I find that if I bypass IPVS and
> ssh to the CentOS 6 director machine, and then ssh from there to one
> of the internal hosts, X applications are as fast as the CentOS 5
> cluster through IPVS.
>
> I also tried manually setting up a DNAT forwarding rule
> on the CentOS 6 director machine, like this:
>
> iptables -A PREROUTING -t nat -p tcp -d my.host.edu --dport 2201 -j DNAT
> --to host1.internal:22
> iptables -I FORWARD -p tcp -s -d host1.internal --dport 22 -j ACCEPT
>
> If I then ssh to my.host.edu:2201 (ending up on host1.internal),
> X applications are as fast as on CentOS 5 through IPVS.
>
> Any suggestions on how I can debug this? The IPVS configurations
> on the two clusters are identical. What should I be looking at?
>
> Thanks in advance for any advice.
>
> Bryan
I saw this problem, if the tcp checksum calculation was done on the interface.
Please use ethtool to switch tcp-checksum off in the IF driver.
--
Dr. Michael Schwartzkopff
Guardinistr. 63
81375 München
Tel: (0162) 1650044
Fax: (089) 620 304 13
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