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On Tue, 22 Jul 2008, Marco Lorig wrote:
Both "directors" are connected via GRE. The first director
starts routing to the second one through the tunnel as
soon as the realservers behind it aren´t available
anymore. So it "turns off" the ipvsadm and switches itself
to a routing instance.
neat.
How do the clients know which datacenter to route to?
The second director, which also serves clients and servers
at its location by ipvsadm, starts another ipvsadm
instance on the GRE interface and is receiving routed
packets from the first director through GRE tunnel.
I see.
can you set mss on this interface?
ip_vs() does all sorts of things to the interface. I don't
expect anyone has tried LVS on a gre interface.
client->director1->gre-tunnel->director2->realserver?
I assume you have two directors in some standard failover
setup and only one is directing when your LVS is up?
It isn´t a typical failover scenario. On each location are
two machines (master/slave). The failover I´m talking
about is switching between datacenters.
got it.
If the realservers after director1 at location 1 aren´t
available anymore, the director1 starts normal routing
operation through tunnel to the other director2 at
location 2, which handles it´s own ipvsadm instances,
clients and realservers. The director2 now serves client
from location 1 with servers at location 2 through GRE
Tunnel.
the copy has nothing to do with LVS? ie you can do the copy
when there is nothing in the ipvsadm table in the 2nd
(inactive) director, but as soon as you put entries into
ipvsadm on the backup director, the gre tunnel breaks?
Making a connection from client n, location 1, to an
address on director 1, the director1 routes the packets
through the tunnel to location 2. Without running ipvsadm
on director 2, location2, the connection establishes
correctly and the a 600Kb file transfer works fine.
Starting ipvsadm on the gre interface of director2,
location2, makes the file transfer hang due to mtu issues,
I presume.
Horms:
any ideas? This worked with a 2.4.x kernel on the directors
and broke when he moved to 2.6.x.
(Any code fixes aren't likely to arrive in time to help
here.) What if you use two nics, one for the gre tunnel with
mss set and one for ipvsadm?
All instances on ipvsadm breaks the tunnel except if a
client connects before to the realserver directly as is
explained in the "update" email, I sent previously.
I didn't get this. You have a route from the client to
director1, through the gre tunnel, to director2 (with no
ipvsadm rules) to the realserver? (the realserver has a
public IP?)
Joe
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