Mailing List Archive: Linux Virtual Server: Users

[lvs-users] Sync table PIRANHA (DIRECT ROUTING) works only long lasting connections

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sp4wn.root at gmail

Oct 27, 2009, 8:24 AM

Post #1 of 4 (842 views)
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[lvs-users] Sync table PIRANHA (DIRECT ROUTING) works only long lasting connections

I heard the following about flow of "master/bakcup" sync (piranha + dr ):

Once a connection is established, the master sync daemon (on the active
director) sends data to the backup sync daemon (on the backup director).
The backup director is then aware of an established connection. If the
primary director fails, the backup will take over and still forward packets
from an established connection to the right reral server.

This works fine on long lasting connections (interactive sessions like FTP,
telnet, SSH and so on) but doesn't on short connections (http without
keepalive for example).

Is it true ? if is true I think the better way to solve this is implement
some solution like conntrack-tools (netfilter).
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leon at linux

Oct 27, 2009, 12:51 PM

Post #2 of 4 (794 views)
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Re: [lvs-users] Sync table PIRANHA (DIRECT ROUTING) works only long lasting connections [In reply to]

On Tue, 2009-10-27 at 13:24 -0200, Raul da Silva {Sp4wn} wrote:
> I heard the following about flow of "master/bakcup" sync (piranha + dr ):
>
> Once a connection is established, the master sync daemon (on the active
> director) sends data to the backup sync daemon (on the backup director).
> The backup director is then aware of an established connection. If the
> primary director fails, the backup will take over and still forward packets
> from an established connection to the right reral server.
>
> This works fine on long lasting connections (interactive sessions like FTP,
> telnet, SSH and so on) but doesn't on short connections (http without
> keepalive for example).
>
> Is it true ? if is true I think the better way to solve this is implement
> some solution like conntrack-tools (netfilter).

I can't test it, because my version of ipvsadm (ipvsadm v1.24 2005/12/10
(compiled with getopt_long and IPVS v1.2.1)) the sync daemons don't work
at all :( But AFAIK it should work on all connection types.

But you could try to alter the values
in /proc/sys/net/ipv4/vs/sync_threshold. By default it's set to '3 50'
meaning after 3 packets the connection gets synchronized and each next
50 packets will cause the connection to sync. Try lowering these values
and experiment if this helps you.

You could also see:

http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.server_state_sync_demon.html

which has a piece on piranha and sync daemons.

--
Léon

_______________________________________________
Please read the documentation before posting - it's available at:
http://www.linuxvirtualserver.org/

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sp4wn.root at gmail

Oct 27, 2009, 1:56 PM

Post #3 of 4 (784 views)
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Re: [lvs-users] Sync table PIRANHA (DIRECT ROUTING) works only long lasting connections [In reply to]

A/C>

I made this tests before, but don't have a effect, but tks for your opinion.

Tks,

On Tue, Oct 27, 2009 at 5:51 PM, L.S. Keijser <leon [at] linux> wrote:

> On Tue, 2009-10-27 at 13:24 -0200, Raul da Silva {Sp4wn} wrote:
> > I heard the following about flow of "master/bakcup" sync (piranha + dr ):
> >
> > Once a connection is established, the master sync daemon (on the active
> > director) sends data to the backup sync daemon (on the backup director).
> > The backup director is then aware of an established connection. If the
> > primary director fails, the backup will take over and still forward
> packets
> > from an established connection to the right reral server.
> >
> > This works fine on long lasting connections (interactive sessions like
> FTP,
> > telnet, SSH and so on) but doesn't on short connections (http without
> > keepalive for example).
> >
> > Is it true ? if is true I think the better way to solve this is implement
> > some solution like conntrack-tools (netfilter).
>
> I can't test it, because my version of ipvsadm (ipvsadm v1.24 2005/12/10
> (compiled with getopt_long and IPVS v1.2.1)) the sync daemons don't work
> at all :( But AFAIK it should work on all connection types.
>
> But you could try to alter the values
> in /proc/sys/net/ipv4/vs/sync_threshold. By default it's set to '3 50'
> meaning after 3 packets the connection gets synchronized and each next
> 50 packets will cause the connection to sync. Try lowering these values
> and experiment if this helps you.
>
> You could also see:
>
>
> http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.server_state_sync_demon.html
>
> which has a piece on piranha and sync daemons.
>
> --
> L�on
>
>
> _______________________________________________
> Please read the documentation before posting - it's available at:
> http://www.linuxvirtualserver.org/
>
> LinuxVirtualServer.org mailing list - lvs-users [at] LinuxVirtualServer
> Send requests to lvs-users-request [at] LinuxVirtualServer
> or go to http://lists.graemef.net/mailman/listinfo/lvs-users

--
Att,

--==========================--
Raul da Silva Leite
sp4wn.root [at] gmail
Linux Consultant / Red hat Brasil
RHCE / LPI-II / ITIL / RHCI / RHCA / RHCSS / RHCDS
+55 11 8504-3200
--==========================--
_______________________________________________
Please read the documentation before posting - it's available at:
http://www.linuxvirtualserver.org/

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horms at verge

Oct 30, 2009, 6:25 PM

Post #4 of 4 (773 views)
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Re: [lvs-users] Sync table PIRANHA (DIRECT ROUTING) works only long lasting connections [In reply to]

On Tue, Oct 27, 2009 at 01:24:58PM -0200, Raul da Silva {Sp4wn} wrote:
> I heard the following about flow of "master/bakcup" sync (piranha + dr ):
>
> Once a connection is established, the master sync daemon (on the active
> director) sends data to the backup sync daemon (on the backup director).
> The backup director is then aware of an established connection. If the
> primary director fails, the backup will take over and still forward packets
> from an established connection to the right reral server.
>
> This works fine on long lasting connections (interactive sessions like FTP,
> telnet, SSH and so on) but doesn't on short connections (http without
> keepalive for example).
>
> Is it true ? if is true I think the better way to solve this is implement
> some solution like conntrack-tools (netfilter).

Hi Raul,

there are some implementation details relating to packet counts and
connection synchronisation that can influence the non-synchronisation
of packets, but I'm not sure that they would cause the effect that you
describe.

The details are that there is a proc value, sync_threshold which can
be set to between 0 and 49 with a default of 3. Once a connection has
received this many packets it will be queued for synchronisation. It will
then be re-synchronised every 50 packets.

_______________________________________________
Please read the documentation before posting - it's available at:
http://www.linuxvirtualserver.org/

LinuxVirtualServer.org mailing list - lvs-users [at] LinuxVirtualServer
Send requests to lvs-users-request [at] LinuxVirtualServer
or go to http://lists.graemef.net/mailman/listinfo/lvs-users

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