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Re: [lvs-users] Could LVS/DR cause a bottleneck with media servers?

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] Could LVS/DR cause a bottleneck with media servers?
From: Malcolm Turnbull <malcolm@xxxxxxxxxxxxxxxx>
Date: Wed, 16 Feb 2011 12:13:05 +0000
On 16 February 2011 02:56, Roger Littin <roger@xxxxxxxxxxxxx> wrote:
> Hi,
>
> I have a set up using ldirectord in direct routing to 30 media servers.
>
> The director is a dell R210 4 core with 8GB memory and has 2 1Gbps network 
> connections, 1 public & 1 private.
>
> Each real server is a Dell R610 16 core with 12GB memory and has the same 
> network connections as above.
>
> All the servers are running centos 5.
>
> According to the data center, these servers are connected to pairs of 40Gb 
> switches and there is ample capacity.
>
> What happens is when the connections per real server get to around 1000 – 
> 1200 concurrent connections, the bandwidth outgoing per server wont go above 
> about 250Mbps which relates to about 7.5Gbps across all servers.  At that 
> time is when the complaints start coming in about stream problems.
>
> I guess the question is could the director somehow be limiting the throughput 
> on the real servers or is the dc not telling the truth about?
> The bandwidth going through the nics on the director is around 50 – 75Mbps in 
> on the public nic and out on the private nic to the real servers.
>
> Before we started using lvs, we had 10 servers running with round robin dns 
> and these would easily handle 900Mbps each at the same time.
>
> lidrectord config file.
>
> # Global Directives
> checktimeout=10
> checkinterval=5
> #fallback=127.0.0.1:80
> autoreload=yes
> callback="/etc/ha.d/syncsettings.sh"
> logfile="/var/log/ldirectord.log"
> #logfile="local0"
> #emailalert="admin@xxxxx"
> #emailalertfreq=3600
> #emailalertstatus=all
> quiescent=no
>
> virtual=147
>        real=172.31.214.12 gate 100
>        real=172.31.214.13 gate 100
>        real=172.31.214.14 gate 100
>        real=172.31.214.15 gate 100
>        real=172.31.214.16 gate 100
>        real=172.31.214.17 gate 100
>        real=172.31.214.18 gate 100
>        real=172.31.214.19 gate 100
>        real=172.31.214.21 gate 100
>        real=172.31.214.22 gate 100
>        real=172.31.214.23 gate 100
>        real=172.31.214.24 gate 100
>        real=172.31.214.25 gate 100
>        real=172.31.214.26 gate 100
>        real=172.31.214.28 gate 100
>        real=172.31.214.29 gate 100
>        real=172.31.214.30 gate 100
>        real=172.31.214.31 gate 100
>        real=172.31.214.32 gate 100
>        real=172.31.214.33 gate 100
>        real=172.31.214.34 gate 100
>        real=172.31.214.35 gate 100
>        real=172.31.214.36 gate 100
>        real=172.31.214.37 gate 100
>        real=172.31.214.38 gate 100
>        real=172.31.214.39 gate 100
>        real=172.31.214.40 gate 100
>        real=172.31.214.41 gate 100
>        real=172.31.214.42 gate 100
>        scheduler=wlc
>        protocol=fwm
>        persistent=60
>        netmask=255.255.255.255
>        service=http
>        checkport=1935
>        request="/"
>        receive="Wowza Media Server 2"
>
> iptables
>
> *mangle
> :PREROUTING ACCEPT [438:421747]
> :INPUT ACCEPT [438:421747]
> :FORWARD ACCEPT [0:0]
> :OUTPUT ACCEPT [95:14749]
> :POSTROUTING ACCEPT [122:21354]
> -A PREROUTING –d *.*.*.147 -p tcp -m tcp --dport 80 -j MARK --set-mark 0x93
> -A PREROUTING -d *.*.*.147 -p tcp -m tcp --dport 443 -j MARK --set-mark 0x93
> -A PREROUTING -d *.*.*.147 -p tcp -m tcp --dport 554 -j MARK --set-mark 0x93
> -A PREROUTING -d *.*.*.147 -p tcp -m tcp --dport 1935 -j MARK --set-mark 0x93
> -A PREROUTING -d *.*.*.147 -p udp -m udp --dport 6970:9999 -j MARK --set-mark 
> 0x93
> COMMIT
>
> the main port that is used is 1935.
>
> Thanks in advance.
>
> Regards,
>
> Roger.
> _______________________________________________
> Please read the documentation before posting - it's available at:
> http://www.linuxvirtualserver.org/
>
> LinuxVirtualServer.org mailing list - lvs-users@xxxxxxxxxxxxxxxxxxxxxx
> Send requests to lvs-users-request@xxxxxxxxxxxxxxxxxxxxxx
> or go to http://lists.graemef.net/mailman/listinfo/lvs-users


Roger,

My gut would say that your switch is getting saturated (not the director).
I wonder if you could get some of the servers to reply to a different
switch (local subnet) but still through the director i.e.
prove the director can can more load if the outgoing traffic is
through a different switch.
Also CPU load on the director is a pretty good indicator of stress.
We've had customers doing similar kind of load (but every setup is different).


-- 
Regards,

Malcolm Turnbull.

Loadbalancer.org Ltd.
Phone: +44 (0)870 443 8779
http://www.loadbalancer.org/

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