[lvs-users] R: How ldirectord polls real servers

Guglielmo Abbruzzese g.abbruzzese at resi.it
Wed Apr 24 09:19:04 BST 2013


In case of tcp protocol, in order to check the connection of a service of
mine running on realserevrs  ("service=none") I already set " connect" as a
checktype; so I assume this setting is the best choice even if such service
should be configured for udp communication.

Should such service be stopped for some reason, my hope is its node should
be removed from the ldirector's realservers list    

Thank you all for your time
Regards
G.

-----Messaggio originale-----
Da: lvs-users-bounces at linuxvirtualserver.org
[mailto:lvs-users-bounces at linuxvirtualserver.org] Per conto di Malcolm
Turnbull
Inviato: martedì 23 aprile 2013 18:26
A: LinuxVirtualServer.org users mailing list.
Oggetto: Re: [lvs-users] How ldirectord polls real servers

Gugliemo,

Ldirectord has various different health checking methods.

For a simple TCP based service you could use the 'connect' check i.e.
Can I do a TCP open on that port?
For UDP you would probably just use a ping check as it is connectionless.

The various methods are pretty well documented in the man page.


On 23 April 2013 16:42, Guglielmo Abbruzzese <g.abbruzzese at resi.it> wrote:
> Hi,
> as far as you know where can I find a detailed  
> description/documentation about how ldirectord polls the realservers 
> in order to realize if the node should be actually removed from the
cluster?
>
> For sure, " ldirectord monitors the health of the real servers by 
> periodically requesting a known URL and checking that the response 
> contains an expected response. If a real server fails then the server 
> is removed and will be reactivated once it comes back on line.".
>
> But what if the real servers implement a custom tcp or udp service?
> In case of a tcp persistent connection, what if there is no data flow 
> for a while (shall I rely just on the 'persistent' timeout)?
> And what about a cistom udp server?
>
> Is there a way to use tcpdump in order to detect such evidence?
>
> Thanks in advance for your advice,
> Regards
> G.
>
>
>
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--
Regards,

Malcolm Turnbull.

Loadbalancer.org Ltd.
Phone: +44 (0)870 443 8779
http://www.loadbalancer.org/

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