Load balancing with multiple DB2 Connect servers

ramesh bala

Load balancing with multiple DB2 Connect servers
Folks, we are contemplating having 2 DB2 Connect production servers to provide some redundancy in the event of critical hardware failure in one of the servers. I am wondering (hard) how the issues of load balancing etc would be handled. I am hoping to keep this transparent to applications. In ...well ..I have to say it....net8 of the 'O' database there is built in redundancy/Load balancing in the networking piece in case one Listener goes down, I cannot imagine good ol DB2 connect being far behind, but from my initial read on the topic I am not hopeful.

I have posted this twice before unsuccessfully, please Any ideas to share would be very welcome


TIA
Ramesh Bala



Leon Katsnelson

Re: Load balancing with multiple DB2 Connect servers
(in response to ramesh bala)
Redundancy for DB2 Connect servers is very easy to achieve (with few
exceptional situations). DB2 Connect servers are very much like web servers
in a sense that they do not hold any state information (except in the case
of 2-phase commit transactions). This means that typical solutions that you
apply to web servers work very well for DB2 Connect servers. These include
using off the shelf "virtual IP" hardware boxes such a s CISCO Local
Director and Distributed Director, BigIP F5, Sonic Wall, Altheon etc. etc.
etc. Pretty much every network vendor makes these devices now a days and I
am willing to bet you have a few in your shop. Talk to your friendly
network people. There is nothing special really required to configure DB2
Connect to work with these devices. The only thing you have to remember is
to ask your network admin to define a "sticky port" for you. Different
vendors may refer to this by another name but in general network admins
should know what you mean when you say "sticky port". IBM WebSphere Edge
Server provides very similar function but in software instead of having a
separate hardware device. The key point in here is to create a cluster of
DB2 Connect servers and make it look like a single box with a single IP
address. All of these solutions do exactly that. If there is an outage on
one server in the cluster, work is directed to other servers with any
awareness of the failure by the application.

You can also explore OS fail-over capabilities such as HACMP, Windows
Cluster Server, SUN Clusters etc. DB2 Connect works with all of these are
not as elegant as the "virtual IP" solution as all of these have some
take-over and give-back lag times. However, if you do need to support
2-phase commit via DB2 Connect, these may be a better solution then virual
IP.

Leon Katsnelson
Manager, DB2 Product Planning
Administration Assistant: Robin Stockfish (905) 413-3632


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Folks, we are contemplating having 2 DB2 Connect production servers to
provide some redundancy in the event of critical hardware failure in one of
the servers. I am wondering (hard) how the issues of load balancing etc
would be handled. I am hoping to keep this transparent to applications. In
...well ..I have to say it....net8 of the 'O' database there is built in
redundancy/Load balancing in the networking piece in case one Listener goes
down, I cannot imagine good ol DB2 connect being far behind, but from my
initial read on the topic I am not hopeful.

I have posted this twice before unsuccessfully, please Any ideas to share
would be very welcome


TIA
Ramesh Bala



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[login to unmask email]



Dave Shapiro

Re: Load balancing with multiple DB2 Connect servers
(in response to Leon Katsnelson)
Ramesh,

For some ideas on load balancing solutions that also handle DB2 Connect product abends or hangs, as opposed to just hardware failure(which the commercial load balancers handle), see the archives for my reply to your previous post dated Dec 10. My experience has been that the DB2 Connect product errors are more of an availability issue than hardware failure. Any serious redundancy solution should incorporate that aspect as well.

Dave

-----Original Message-----
From: [login to unmask email] [mailto:[login to unmask email]
Sent: Monday, January 06, 2003 1:13 AM
To: [login to unmask email]
Subject: Re: Load balancing with multiple DB2 Connect servers


Redundancy for DB2 Connect servers is very easy to achieve (with few
exceptional situations). DB2 Connect servers are very much like web servers
in a sense that they do not hold any state information (except in the case
of 2-phase commit transactions). This means that typical solutions that you
apply to web servers work very well for DB2 Connect servers. These include
using off the shelf "virtual IP" hardware boxes such a s CISCO Local
Director and Distributed Director, BigIP F5, Sonic Wall, Altheon etc. etc.
etc. Pretty much every network vendor makes these devices now a days and I
am willing to bet you have a few in your shop. Talk to your friendly
network people. There is nothing special really required to configure DB2
Connect to work with these devices. The only thing you have to remember is
to ask your network admin to define a "sticky port" for you. Different
vendors may refer to this by another name but in general network admins
should know what you mean when you say "sticky port". IBM WebSphere Edge
Server provides very similar function but in software instead of having a
separate hardware device. The key point in here is to create a cluster of
DB2 Connect servers and make it look like a single box with a single IP
address. All of these solutions do exactly that. If there is an outage on
one server in the cluster, work is directed to other servers with any
awareness of the failure by the application.

You can also explore OS fail-over capabilities such as HACMP, Windows
Cluster Server, SUN Clusters etc. DB2 Connect works with all of these are
not as elegant as the "virtual IP" solution as all of these have some
take-over and give-back lag times. However, if you do need to support
2-phase commit via DB2 Connect, these may be a better solution then virual
IP.

Leon Katsnelson
Manager, DB2 Product Planning
Administration Assistant: Robin Stockfish (905) 413-3632


|
| Subject: Load balancing with multiple DB2 Connect servers |------------|



Folks, we are contemplating having 2 DB2 Connect production servers to
provide some redundancy in the event of critical hardware failure in one of
the servers. I am wondering (hard) how the issues of load balancing etc
would be handled. I am hoping to keep this transparent to applications. In
...well ..I have to say it....net8 of the 'O' database there is built in
redundancy/Load balancing in the networking piece in case one Listener goes
down, I cannot imagine good ol DB2 connect being far behind, but from my
initial read on the topic I am not hopeful.

I have posted this twice before unsuccessfully, please Any ideas to share
would be very welcome


TIA
Ramesh Bala