FAQ

2009-11-10T17:10:32Z

Georg: /* How to compile ipvsadm on difficult Linux distributions */

== General ==
=== What's LVS? ===

[[LVS]] stands for Linux Virtual Server, which is a highly scalable and highly available server built on a cluster of real servers, with the [[load balancer]] running on the Linux operating system. Users interact as if it were a single virtual server.

=== Is LVS software free? ===

Yes! All [[LVS]] software is released under the [http://www.gnu.org/copyleft/gpl.html GNU General Public License (GPL)].

=== Is there a FreeBSD port of LVS software? ===

Yes, there is a FreeBSD port of IPVS, which supports the [[LVS/DR]] and [[LVS/TUN]] methods now. See [http://dragon.linux-vs.org/~dragonfly/htm/lvs_freebsd.htm the LVS On FreeBSD page] for more information.

=== Does LVS cluster support Linux servers only? ===

No, real servers can almost run any operating systems in a LVS cluster, such as Linux, BSDs, Solaris, and Windows. [[LVS/NAT]] balances servers of the operating systems having TCP/IP support, [[LVS/TUN]] requires servers having IP Tunneling protocol, and [[LVS/DR]] requires servers having a non-arp device. Almost all the modern operating systems support non-arp device.

== Performance ==

=== How is the concurrent processing performance of current LVS software? ===

The ultimate performance of LVS depends on hardware that LVS runs on. An ordinary box with a single Pentium III processor and 100Mbps NIC card running [[LVS/DR]] can handle about 10,000 connections per second for web service. We have heard that a powerful box with good hardware and kernel tuning achieved 50,000 connections per second.

=== Can LVS handle more than 1 million simultaneous connections? ===

Yes, LVS can handle much more than 1 million simultaneous connections. One connection just costs 128 bytes in the LVS box, so an LVS box with 1G memory can handle more than 8 million simultaneous connections.

== Setup ==

=== Is there a quick guide to setup LVS ===

Yes, please check the article [[Mini Mini Howto]], which covers setting up LVS quickly on Linux distributions of Fedora Core 4 or later.

=== How do I check to see if my kernel has IPVS enabled? ===

Try to run <tt>"modprobe ip_vs"</tt> and try to see if there is <tt>/proc/net/ip_vs</tt>. If so, your kernel has [[IPVS]] enabled. You can also run <tt>"cat /proc/net/ip_vs"</tt> or <tt>"ipvsadm -Ln"</tt> to see the version number of [[IPVS]].

<pre>
[root@lb4 root]# ipvsadm -Ln
IP Virtual Server version 1.0.11 (size=65536)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
...
</pre>

You could also check your current kernel config (<tt>/proc/config{.gz}</tt> or somewhere in <tt>/boot</tt>) if <tt>CONFIG_IP_VS</tt> is set (located under <tt>Networking support->Networking options->Netfilter</tt> when using <tt>make menuconfig</tt> to configure your kernel).

=== How to compile ipvsadm on different Linux distributions ===

[[Ipvsadm]] is the tool to set up, maintain or inspect the [[IPVS]] table in the Linux kernel. See the article [[compiling ipvsadm on different Linux distributions]] for detailed information.

== Statistics ==

=== How do i get counters from ipvsadm in order to create graphs from? ===

'''Answer 1:'''

The current kernel 2.6 version of ipvsadm (v1.24) supports
ipvsadm --list --stats --numeric --exact
which gives you non-human-readable counters for Connections, Packets and Bytes for each Service Address and Realserver.

'''Answer 2:'''

Install [http://oss.oetiker.ch/rrdtool/ RRDtool] and preferabely [http://www.cacti.net/ Cacti] onto a host of your choice. From your favorite Linux distribution, install the [http://www.net-snmp.org/ Net-SNMP daemon] onto the Loadbalancer host. Apply the [[Net-SNMP-LVS-Module]] to the Net-SNMP daemon. Using RRDtool and/or cacti you may query the Loadbalancer and create all kind of graphs using the statistics the Loadbalancers IPVS-module delivers.

[[Category:LVS Handbook]]

LVSKB - User contributions [en]

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