IPVS - Load Balancing

[fabbie]

Hi guys,
I hope someone can shed some light to my problem.

I recently setup LVS to act as a load balancer for my web servers.

Basically everything worked fine, until i began to test the performance of the load balancer.

I basically have 3 servers in total.
- 1 load balancer (LVS director)
- 2 apache web servers (real server)
The load balancer has been configured to route all port 80 connections to the 2 apache web servers.

I ran apache bench with the setting of 1000 concurrent connections of a total of 2000 request to the load balancer and saw that 900 connections failed.
Eg. ab -c 1000 -n 2000 xxxxxxxx

The result was like this:
Concurrency Level: 1000
Time taken for tests: 9.548 seconds
Complete requests: 2000
Failed requests: 924
(Connect: 0, Receive: 0, Length: 924, Exceptions: 0)
Write errors: 0
Total transferred: 101895760 bytes
HTML transferred: 101322760 bytes
Requests per second: 209.47 [#/sec] (mean)
Time per request: 4774.038 [ms] (mean)
Time per request: 4.774 [ms] (mean, across all concurrent requests)
Transfer rate: 10421.74 [Kbytes/sec] received


I ran the same test directly to the realserver (web server) and all the http connection was successful. This actually proved that the director could not forward all the connections to the realservers. Any idea what caused this?

I've modified the ulimit, but, still fail to forward completely to the realservers.


Any insight will be greatly appreciated. Thank you.

[Irithori]

Transfer rate: 10421.74 [Kbytes/sec] received

Are you using a 100MBit/s NIC or a 1GBit/s NIC in 100MBit/s mode?

[fabbie]

It's a 100Mbps NIC.


ethtool eth1
Settings for eth1:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised auto-negotiation: Yes
Speed: 100Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: pumbag
Wake-on: g
Current message level: 0x00000001 (1)
Link detected: yes