Re: [lvs-users] Sync issue after master reboot

To: "Markhasin, Dan" <dan.markhasin@xxxxxxxxx>
Subject: Re: [lvs-users] Sync issue after master reboot
Cc: "lvs-users@xxxxxxxxxxxxxxxxxxxxxx" <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
From: Julian Anastasov <ja@xxxxxx>
Date: Tue, 25 Feb 2014 10:25:45 +0200 (EET)

On Wed, 12 Feb 2014, Markhasin, Dan wrote:

> Hello,
> We are currently building an LVS cluster with two ldirector servers to ensure 
> HA. Each of these servers has two ipvsadm 1.26 sync daemons running, which we 
> start by:
> On master:
> --start-daemon master --syncid 50
> --start-daemon backup --syncid 51
> On backup:
> --start-daemon master --syncid 51
> --start-daemon backup --syncid 50
> During normal operation there are no issues, connections are made to the 
> master and are synced to the backup. In case the master goes down, the 
> connections seamlessly transfer over to the backup.
> However, in the case of a reboot of the master, after the master is brought 
> back online and the ipvsadm daemons are started, the existing connections 
> from the backup server are not synced to the master - causing them all to 
> disconnect whenever a failback is performed. New connections made to the 
> slave are synced, but the old ones are not.
> I have seen references from the past decade to this problem, but have found 
> no solution for syncing the master and the backup server after the master's 
> reboot. Any help would be greatly appreciated!

        Yes, there is no trigger implemented to sync all
connections at once. But looking at the code I don't see
why sync should stop transferring information. I don't
know what kernel you are using but even connections with
IP_VS_CONN_F_SYNC bit (created while we were backup)
should be synced when we are master. Of course, it can depend
on forwarding methods, fwmark usage, kernel (IPVS sync
protocol) version, netfilter (stateful firewalling dropping
the synced conns), etc. May be you can give more information
and to share more observations.


Julian Anastasov <ja@xxxxxx>

Please read the documentation before posting - it's available at: mailing list - lvs-users@xxxxxxxxxxxxxxxxxxxxxx
Send requests to lvs-users-request@xxxxxxxxxxxxxxxxxxxxxx
or go to

<Prev in Thread] Current Thread [Next in Thread>