[lvs-users] ldirectord question

Aaron West aaron at loadbalancer.org
Fri Jun 20 08:30:27 BST 2014


Thanks Simon, I forgot entirely about quiescence...



On 20 June 2014 02:06, Simon Horman <horms at verge.net.au> wrote:

> 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 at bankservafrica.com> 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 at 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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