Hi. This discussion got me thinking would it be possible for HAproxy to query a
PHP/Perl/Python...-script that returns some kind of numerical information
concerning the server's load. For example HAproxy could check periodically
http://server_name/load_status
where the 'load_status'-script would return something like
performance_index 0.92
Ideally the performance_index should be 1.00, but under heavy load the index
would be lower. HAproxy could then multiply the basic server weight with this
performance_index.
For example there could be three servers
server Aserver 192.168.0.1:80 cookie Acookie check inter 2000 weight
100
server Bserver 192.168.0.2:80 cookie Bcookie check inter 2000 weight
100
server Cserver 192.168.0.3:80 cookie Ccookie check inter 2000 weight
80
If all servers are working optimally under light load all of them would return
a performance_index of 1.00. However if server A should be under heavy load, it
would return performance_index 0.5. The server B is somewhat less loaded
returning performance_index 0.8 and C lightly loaded returning 0.95 the dynamic
weights would be
server A: 100 * 0.5 = 50
server B: 100 * 0.8 = 80
server C: 80 * 0.95 = 76
The beauty is that every administrator could tweak the 'load_status'-script at
his/her heart's will taking into consideration just his/hers own server farm's
typical use and properties by choosing what performance data (CPU usage, CPU
load, io_wait, average/maximum response time...) he/she wants to use when
calculating the performance_index.
Best, B
__________ Information from ESET NOD32 Antivirus, version of virus signature
database 4522 (20091019) __________
The message was checked by ESET NOD32 Antivirus.
http://www.eset.com
