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> When a service is marked persistent all connections from
> CIP to VIP go to same RIP for the specified period. Even for the
> fwmark based services. This works for many independent VIPs.
>
> The other case is fwmark service covering a DNS name.
> I expect comments from users with SSL problems and persistent fwmark
> service. Is there a problem or may be not?
>
> I agree, may be the both cases can be useful:
>
> 1. CIP->VIP
> 2. CIP->FWMARK
>
> Any examples where/why (2) is needed?
>
> But switching the LVS code always to use (2) for the
> persistent fwmark services is possible.
In my opinion, here are some pros and cons of case 2:
===== Pros: =====
-- Improves scheduling, I think, and true load balancing. If someone is
using [W]RR or [W]LC, the LVS box will actually look at the real servers as
a whole rather than separate real server entries for EACH VIP. Does that
make sense?
For example, in my particular configuration I have over one thousand VIPs
which are load balanced onto four RIPs. When I configure the LVS server to
use LC scheduling, I'd like it to look at how many TOTAL connections are
being made to each RIP not how many connections are being made to each RIP
PER VIP. I would like to load balance all one thousand VIPs as a WHOLE onto
the four RIPs rather than load balance EACH VIP.
That is, in some of my less active sites, most of their traffic will
probably hit one VIP just because not much traffic will need to be load
balanced. However, more active sites will hit both servers. The load will
then not be distributed equally among the servers as one server will
probably get not only the active traffic but also the less active traffic
and the other server will only get the more active traffic (in the case of
having two RIPs).
Do you see what I mean?
===== Cons: =====
-- One person on the Internet will keep connecting to the same RIP for many
different VIPs if persistence is turned on
HOWEVER... If this causes a problem, the LVS administrator can do one of two
different things:
1) Rather than load balancing a FWMARK template, go back to load balancing
specific VIPs. The scheduling will then be unique for those particular VIPs.
2) Create multiple FWMARK templates. The scheduling for each template will
be unique.
In my opinion if you group a bunch of IPs together by marking them with an
FWMARK, that you say that you want to load balance all of those
COLLECTIVELY -- almost like load balancing one site.
I'm just saying are there any examples where CIP->FWMARK is not needed?
All the best --
Ted
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