Re: [PATCH] ipvs: add sync_persist_mode flag

To: Aleksey Chudov <aleksey.chudov@xxxxxxxxx>
Subject: Re: [PATCH] ipvs: add sync_persist_mode flag
Cc: lvs-devel@xxxxxxxxxxxxxxx
From: Julian Anastasov <ja@xxxxxx>
Date: Sat, 22 Jun 2013 15:43:26 +0300 (EEST)

On Sat, 22 Jun 2013, Aleksey Chudov wrote:

> > From: Julian Anastasov <ja@xxxxxx>
> > [PATCH] ipvs: add sync_persist_mode flag
> > 
> > Add sync_persist_mode flag to reduce sync traffic
> > by syncing only persistent templates.
> > 
> > 
> I tested the changes on one pair of LAN servers. After turning on
> sync_persist_mode synchronization traffic decreased by 4 times! Also on LVS
> Backup I can see only persist connections.

        Thanks! Can we assume that you have small number
of connections from every client? 1-2 per IP? Or a small
sync_refresh_period value is used? Can you show all these
sync* sysctl parameters that were used?

> First of all the Kernel on both servers have been updated. Then LVS Backup has
> been rebooted to drop all connections. After the reboot sync was disabled and
> all connections counters was zero. When I enabled sync again almost all
> persist connections from LVS Master have been synced to LVS Backup. But also I
> can see 0.04% of the connections in ESTABLISHED state, although they should
> not be there! After disabling sync all connections on LVS Backup completely
> disappear after about 5 minutes.

        Is it possible some of your services to be with
persistence disabled? Because the sync_persist_mode=1 mode
will not affect non-persistent services - their synchronisation
should work as before.

        You can also try to grep for such established conns:

# Find such ESTABLISHED conns
grep ESTAB ip_vs_conn

# and see what kind of conns we have from such client IPs, do
# we have persistence templates, etc.
grep client_ip ip_vs_conn

> After turning on sloppy_tcp IP address have been moved from LVS Master to LVS
> Backup. According to our statistics, most on clients remained on the same real
> servers. I don't see any problems with sloppy_tcp.

        So, at least sloppy_tcp appears to work :)


Julian Anastasov <ja@xxxxxx>
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