CommServer/AIX suppports Cluster and High Availability?

l***@us.ibm.com

2008-01-18 15:11:13 UTC

Post by NIck Dakoronias
Hello Comm server forum users,
Any advise on the following will be much appreciated?
Could you pls advise if IBM Comm Server v6.3 supports
a) AIX hw cluster (HACMP) for high availability/failover purposes?
btw, there is neither relevant reference at CS/AIX system
http://www-306.ibm.com/software/network/commserver/aix/sysreqs/?S_CMP=rnav
http://www-1.ibm.com/support/docview.wss?rs=1005&uid=swg27006996

It is a matter of perspective.
From my perspective it is not CS/AIX which supports HACMP,
but it is HACMP which supports H.A. and failover of CS/AIX.
That is why you won't see HACMP in the CS/AIX System Requirements list.

In other words you have to write HACMP scripts which will
move the CS/AIX resources from the failed system to the
backup system, just like you would for any other application.
CS/AIX does not provide such scripts. They are HACMP scripts.
Remember that in a fail-over case, where the primary AIX system
has gone down, HACMP learns of the failure first, so HACMP
must inform the backup CS/AIX to take over the failed
resources (links, PUs, LUs, etc).

The HACMP people used to sell these scripts as a 'service'.
I assume they still do so. They do have to be customized
for the specific CS/AIX environment, so someone with knowledge
of CS/AIX AND HACMP is needed.

You will need to have an HACMP level with this fix in it:
http://www.ibm.com/support/docview.wss?uid=isg1IY98185
when using it with CS/AIX v6.3.

Post by NIck Dakoronias
b) Load Balancing for TCP/IP based (telnet) session requests?
I have found the alternative of using LoadBalancer/Network
Dispatcher (Websphere Edge),
as per CommServer load balancing redbook SG24-5305-00,
http://www.redbooks.ibm.com/redbooks/pdfs/sg245305.pdf
Is there any other option or altenative?

Other options:
- SLP (mentioned in that redbook), which I don't recommend because:
-- only supported on IPv4 networks
-- uses multicast, which is usually filtered when
crossing a tcp/ip subnet (i.e. at the router).

- a non-IBM external load-balancer, for example:
-- some CISCO routers contain load-balancing capabilities
where the initial session connection is routed to one
of several possible targets. Once the session is
setup, the router just continues to route the packets
from that particular client to that particular server.
-- Nameserver based load balancers. These are programs
that sit in front of a DNS and when the tn3270 client
requests the tcp/ip address of a tn3270 server name,
it picks one from a group of choices. The tn3270
client then connects to that unique target tcp/ip
address like normal.
In both those cases the tn3270 client and tn3270 server
know nothing about the load-balancing being done.

Paul Landay