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On Fri, Jun 10, 2005 at 02:20:39PM +1100, Andy Nguyen wrote:
> Hi all,
>
> I am having a HA setup with two load balancers running ldirectord talking to
> two dns servers using direct routing:
>
> 10.0.1/24 192.168.1/24
> |-[DNS1]-|
> ->---|-[LB1 ]-|
> ->---|-[LB2 ]-|
> |-[DNS2]-|
>
> I am testing by sending DNS queries using queryperf to the VIP from outside
> the subnet.
>
> By quickly failing a DNS server (stopping bind9) while it was the active
> server, I was able to have a UDP connection in the connection table that
> never expires.
> The timer keeps counting down to 0, then starts again from 60.
>
> lb2:/etc/ha.d# ipvsadm -Lnc
> IPVS connection entries
> pro expire state source virtual destination
> UDP 00:46 UDP 10.1.0.2:32799 10.10.10.1:53 192.168.1.22:53
> lb2:/etc/ha.d# ipvsadm -Ln
> IP Virtual Server version 1.2.1 (size=4096)
> Prot LocalAddress:Port Scheduler Flags
> -> RemoteAddress:Port Forward Weight ActiveConn InActConn
> UDP 10.10.10.1:53 wrr
> -> 192.168.1.21:53 Route 5 0 0
> -> 10.0.1.22:53 Route 0 0 0
> -> 10.0.1.21:53 Route 1 0 0
> -> 192.168.1.22:53 Route 0 0 1
>
> lb2:/etc/ha.d# sysctl -A|grep vs
> net/ipv4/vs/nat_icmp_send = 0
> net/ipv4/vs/sync_threshold = 3 50
> net/ipv4/vs/expire_quiescent_template = 1
> net/ipv4/vs/expire_nodest_conn = 1
> net/ipv4/vs/cache_bypass = 0
> net/ipv4/vs/secure_tcp = 0
> net/ipv4/vs/drop_packet = 0
> net/ipv4/vs/drop_entry = 0
> net/ipv4/vs/am_droprate = 10
> net/ipv4/vs/amemthresh = 1024
>
> lb2:/etc/ha.d# ipvsadm -v
> ipvsadm v1.24 2003/06/07 (compiled with getopt_long and IPVS v1.2.1)
>
> lb2:/etc/ha.d# uname -a
> Linux lb2 2.6.11.10.05052702 #1 SMP Fri May 27 18:17:56 EST 2005 i686
> GNU/Linux
>
>
> Queryperf uses the same source port for the queries, so when this happens
> the queries are still sent to 192.168.1.22 even with the realserver marked
> as not available.
>
> Has anyone seen anything like this?
Yes, there was a bug in LVS's connection handling, which sounds
suspiciouly like the problem you are seeing.
Can you try the attached patch (or a newer kernel).
--
Horms
0001.d9fa0f392b20b2b8e3df379c44194492a2446c6e.patch
Description: Text document
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