Having client of Squid server with opened persistent connection
causing the LVS balancing forwarding new connections to the other node
only.
LVS configuration and status:
~ $ ipvsadm -Ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 10.x.y.55:3128 lblcr
-> 10.x.y.50:3128 Route 1 26 440
-> 10.x.y.51:3128 Route 1 1 0
Once the Squid on 51 node is restarted, the connections are
distributed via both nodes again. After "some time" only one
connection remain opened/active via 51 node. Always caused by the same
client opening HTTP persistent connection to specific domain.
Running on updated Debian9.
~ $ uname -a
Linux proxy01 4.9.0-5-amd64 #1 SMP Debian 4.9.65-3+deb9u2 (2018-01-04)
x86_64 GNU/Linux
Change of weight to 20 caused all the connections going through both nodes.
~ $ ipvsadm -Ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 10.x.y.55:3128 lblcr
-> 10.x.y.50:3128 Route 20 21 248
-> 10.x.y.51:3128 Route 20 25 42
Seems that opening 20 persistent connections via one node will cause
the similar behavior like with one connection and weight set to one.
With weight of 200 set on both nodes, all connections were forwarded
to one node only.
How to understand the weight for lblcr scheduler? What is the best
practice for balancing persistent connections?
According the LVS How-to [1], setting the LVS persistence for VIP
might help to let LVS forward connections across all nodes
independently on weight value. Is this my assumption correct?
[1]
http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.persistent_connection.html
--
Peter
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