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Re: [lvs-users] ldirectord question

To: LinuxVirtualServer.org users mailing list. <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>, Aaron West <aaron@xxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] ldirectord question
From: Ilo Lorusso <IloL@xxxxxxxxxxxxxxxxxx>
Date: Fri, 20 Jun 2014 08:02:16 +0000
Thanks for the feedback,

Once we have scheduled new connections to the new real server and we have this 
existing connection  using quiescence ,

Why can't we move that existing connection to another real server ?

I know firewalls can move existing connections and TCP states between failover 
pairs 

-----Original Message-----
From: lvs-users-bounces@xxxxxxxxxxxxxxxxxxxxxx 
[mailto:lvs-users-bounces@xxxxxxxxxxxxxxxxxxxxxx] On Behalf Of Simon Horman
Sent: Friday, June 20, 2014 3:07 AM
To: Aaron West
Cc: LinuxVirtualServer.org users mailing list.
Subject: Re: [lvs-users] ldirectord question

Hi,

On Thu, Jun 19, 2014 at 06:20:02PM +0100, Aaron West wrote:
> Hi Ilo,
> 
> To my knowledge a real server failing a health check done by an agent 
> such as ldirectord/keepalived is pulled from the LVS table.
> 
> This will break any established connections to this server. A new 
> connection should then start on a remaining live server on the next 
> click/refresh for something like a web application or next connection 
> retry for something else.

It is possible, though not necessarily desirable, to avoid breaking existing 
connections by using quiescence. On the LVS side this is implemented by setting 
a server weight to zero, which allows existing connections to continue but 
prevents new connections from being "scheduled".

This is exposed in ldirectord as a quiescence setting by which it sets the 
weight of a real-server to zero rather than removing it in the case where its 
health check fails.

I am not familiar with keepalived but I suspect it has a similar feature.

> How this affects your app/users depends on your application design, 
> mostly HTTP sessions would be fine while things like RDP/SSH/HTTPS 
> would require you to reconnect/re-authenticate.
> 
> Regards
> 
> Aaron West
> 
> 
> On 19 June 2014 16:42, Ilo Lorusso <IloL@xxxxxxxxxxxxxxxxxx> wrote:
> 
> > Hi ,
> >
> >
> > I have a general question of how ldirectord works, I have setup my 
> > virtual service and real servers
> >
> > I have an active connection and traffic is flowing through to the 
> > real server perfectly as shown below
> >
> >
> > I want to know is it possible to move an established connection 
> > between the real servers without resetting or reestablishing the TCP 
> > connection ?
> >
> > [root@lbmaster ~]# ipvsadm -Ln
> > IP Virtual Server version 1.2.1 (size=32768) Prot LocalAddress:Port 
> > Scheduler Flags
> >   -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
> > TCP  172.16.162.190:40054 wlc persistent 300
> >   -> 172.16.162.199:40054         Masq    100    1          0
> >   -> 172.16.162.200:40054         Masq    99     0          0
> >
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_______________________________________________
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or go to http://lists.graemef.net/mailman/listinfo/lvs-users

BankservAfrica is a BBBEE level 4 procurement contributor

This e-mail and its attachments, if any, are subject to BankservAfrica's e-mail 
disclaimer which is available on 
http://www.bankservafrica.com/Contactus/EmailDisclaimer.aspx 

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