Apache HTTP proxying for load balancing only to a group of non-clustered WL servers

          Hi,
          We're running WL Server 6.1 SP 2 on Solaris 2.8.
          For the Apache HTTP proxy plugin, if you use the WebLogicCluster http.conf option,
          do the WL servers you want to load balance across have to be part of a WebLogic
          cluster (if you are prepared to do without failover, as I know it would need to be
          a proper WL cluster to replicate session info for failover). Can you load balance
          across a group of non-clustered WL servers, and maintain the user session to the
          one WL server so that it doesn't switch between servers on alternate requests for
          the same user session, or must the servers be configured as a WebLogic cluster?
          Paul
          We find that if you have a collection of WL servers that are not configured as a
          cluster, that it will load balance alternate requests to each server, but it will
          not pin a user to a single machine according to their session so for 2 servers, 2
          differetn sessions get created, one on each machine.
          Is this because it doesn't normally do this, but sends the user alternately to a
          primary then secondary which works in a cluster because the session is replicated.
          I thought the secondary was only used when the primary failed.

We're running WL Server 6.1 SP 2 on Solaris 2.8.          >
          > For the Apache HTTP proxy plugin, if you use the WebLogicCluster http.conf
          option,
          > do the WL servers you want to load balance across have to be part of a
          WebLogic
          > cluster (if you are prepared to do without failover, as I know it would
          need to be
          > a proper WL cluster to replicate session info for failover). Can you load
          balance
          > across a group of non-clustered WL servers, and maintain the user session
          to the
          > one WL server so that it doesn't switch between servers on alternate
          requests for
          > the same user session, or must the servers be configured as a WebLogic
          cluster?
          You don't have to use the clustering option. To get failover, you'll have to
          use the JDBC persistence option of WL.
          > We find that if you have a collection of WL servers that are not
          configured as a
          > cluster, that it will load balance alternate requests to each server, but
          it will
          > not pin a user to a single machine according to their session so for 2
          servers, 2
          > differetn sessions get created, one on each machine.
          >
          > Is this because it doesn't normally do this, but sends the user
          alternately to a
          > primary then secondary which works in a cluster because the session is
          replicated.
          > I thought the secondary was only used when the primary failed.
          The primary/secondary stuff requires clustering. If Apache continues to
          "load balance" after the first request, you need to either use JDBC session
          persistence or use a different load balancer (like mod_jk for Apache or a
          h/w load balancer with support for sticky).
          Peace,
          Cameron Purdy
          Tangosol, Inc.
          http://www.tangosol.com/coherence.jsp
          Tangosol Coherence: Clustered Replicated Cache for Weblogic
          "Paul Hammond" <[email protected]> wrote in message
          news:[email protected]...
          >

Similar Messages

Clustering for load balancing only

I wish to set up 2 WLS 8.1 machines to run an application independently to
          share load (no replication of sessions, beans etc).
          Can I create a cluster for the two servers and not turn on any session or
          bean replication, then configure the IIS or Apache plug-in to use the
          cluster and therefore create some load balancing?
          Chris


Chris,
          Yes you can certainly use a Cluster simply for load balancing. There is no
          mandate that you have to take advantage of session state replication in the
          cluster.
          ~Ryan Upton
          "Chris Steains" <[email protected]> wrote in message
          news:[email protected]..
          > I wish to set up 2 WLS 8.1 machines to run an application independently to
          > share load (no replication of sessions, beans etc).
          >
          > Can I create a cluster for the two servers and not turn on any session or
          > bean replication, then configure the IIS or Apache plug-in to use the
          > cluster and therefore create some load balancing?
          >
          >
          > Chris
          >
          >

Using reverse proxy for load balancing

Hello,
i have succesfully configured a reverse proxy ( Sun Web Server 7 ) to balance load between two application servers ( Sun Application Server 9.1), however i do not want randon assignment of requests using a round robin algorithm ( default option in Sun Web Server 7) but rather i want to apply a 80/20 rule so that one application server will receive 80% of the requests and the other will receive 20%.
Is there a way of performarming such a task.
your help is really appreciated.
thank you

thank you for the reply,
actually i tried it yesterday and it seems to work.
in my reverse proxy settings i added one server two times and the other once and 66% of the requests were forwarded to the first server.
now i have enabled the scenario that you are mentioning above and i so far requests seem to be proceced using the 80% 20% scenario.

Reverse Proxy and Load Balancer for SMP 2.3 and Agentry Application

Hi Expert,
I'm putting in place a mobile solution composed by SMP 2.3 SPS 4 and SAP ECC 6.0. In the SMP 2.3 I created the agentry server and I have deployed my agentry application.
My SMP/Agentry infrastructure is composed by two servers therefore I need a load balancer for balance the load into the several servers. Furthermore I need to use a reverse proxy in my DMZ zone.
Based on what indicated in the SAP note "1904213 - SAP Mobile Platform Server Release Information" the Apache Reverse Proxy is not supported for Agentry clients. Agentry uses nginx for Reverse Proxy.
I also found the following document How-to-Guide for Reverse Proxy and Load Balancing in SAP Mobile Platform 3.x that explain how to set-up a reverse proxy and load balancer with nginx and apache.
Both the SAP note and the HOW to document are refereed to SMP 3.0 and not to SMP 2.3.
I would know if the NGINX must be used also for SMP 2.3.
Any suggestion/information is appreciated.
Thanks in advance
g.

Please see Agentry Network Landscapes

Using ACE for proxy server load balancing

Hello groups,
I wanted to know your experiences of using ACE for proxy server load balancing.
I want to load balance to a pool of proxy servers. Note: load-balancing should be based on the HTTP URL (i can't use source or dest. ip address) so that
a certain domain always gets "cached/forwarded" to the same proxy server. I don't really want to put matching
criteria in the configuration (such as /a* to S1, /b* to S2, /c* to S3,etc..), but have this hash calculated automatically.
Can the ACE compute its own hash based on the number of "online" proxy servers ? ie. when 4 servers are online, distribute domains between 1,2,3,4 evenly.
Should server 4 fail, recalculate hash so that the load of S4 gets distributed across the other 3 evenly. Also load-balancing domains of S1 ,S2 and S3 should not change if S4 fails.....
regards,
Geert

This is done with the following predictor command:
Scimitar1/Admin# conf t
Enter configuration commands, one per line. End with CNTL/Z.
Scimitar1/Admin(config)# serverfarm Proxy
Scimitar1/Admin(config-sfarm-host)# predictor hash ?
address         Configure 'hash address' Predictor algorithms
content         Configure 'hash http content' Predictor algorithms
cookie          Configure 'hash cookie' Predictor algorithms
header          Configure 'hash header' Predictor algorithm
layer4-payload Configure 'hash layer4-payload' Predictor algorithms
url             Configure 'hash url' Predictor algorithm
Scimitar1/Admin(config-sfarm-host)# predictor hash url
It does hash the url and the result takes into account the number of active proxies dynamically.
This command has been designed for this kind of scenario that you describe.
Gilles.

CF8/JRun4 Cluster for Load Balancing

Does anyone have an example of how to set up a CF8/JRun4
cluster for load balancing?
I have three servers:
x004 - Linux - Apache2 (10.0.0.54,10.1.0.54)
x020 - Linux - JRun4/CF8 (10.0.0.70,10.1.0.70)
x021 - Linux - JRun4/CF8 (10.0.0.71,10.1.0.71)
Every server in our network has two network cards. One
network card is attached to 10.0.x.x which has a gateway to the
internet and runs at 100Mbps and is firewalled, and the other is
attached to 10.1.x.x which runs at 1Gbps and is internal with no
gateway. I'm trying to set it up so web traffic arrives on
10.0.0.54 into Apache and mod_jrun20 bootstraps a cluster named
STST using 10.1.0.54 which consists of STST_x020 coldfusion server
running on x020 and STST_x021 running on x021. I want the
communications between JRun4 on x020 and x021 to occur on the
10.1.x.x network and eventhough JRun and ColdFusion will only use
the 10.1.x.x network I still need the 10.0.x.x network card
attached for other purposes which require a gateway. I have
installed JRun4/CF8 about 10 times already and it seems I have no
control over what network JRun4 clusters on... sometimes it will
communicate on one, sometimes the other and without being able to
set which network is being used there always seems to be "network
error" on at least one of the two CF8 servers. I was able to get
everything working fine by disabling the network cards on the
10.0.x.x network and re-installing everything... but as soon as I
added the network cards back the whole thing was broken again.
How is this supposed to work? Most of the examples are either
no clustering or clustering on the same machine with Apache running
on the same box... I don't see any clustering across machines
examples.
How do I install a connector on a web server which doesn't
have JRun on it and get wsconfig to connect to a multi-machine
cluster when wsconfig only accepts a single IP address as a host
and the cluster is not listed?
How do I get JRun to bind to a specific network card?
Does this work if I choose a J2EE server other than JRun?
Any help anyone can provide is greatly appreciated. I'm
getting close to giving up which means staying on the non-clustered
environment and figuring out how we can deal with scalability by
switching to something else.

The article at
http://www.adobe.com/go/1e8e9170
is specific to configuring two or more cluster nodes that reside on
separate networks, e.g. 10.0.1.0/24 and 10.0.2.0/24. (The article
doesn't state it, but you can only use unicast peers if your
cluster nodes host a single instance of JRun or multiple instances
of JRun in the same cluster domain. When performing unicast
discovery, JRun looks for all Jini groups and not just the cluster
group.)
Anyhow, that's not your problem. The simplest solution is you
haven't enabled the jrun.servlet.jrpp.JRunProxyService service. I'm
most familiar with the Windows version of JRun, but I'm assuming
the directory structure is similar across platforms. In
<jrun_root>/servers/<name>/SERVER-INF/jrun.xml, set the
deactivated attribute of the jrun.servlet.jrpp.JRunProxyService
service to false and restart JRun. You should now see JRun
listening on the appropriate port. (The default for the first
manually created instance is 51000.) You can limit the proxy
service to a single interface using the interface attribute.
If you have enabled the proxy service, verify your security
settings in <jrun_root>/lib/security.properties. It's usually
best to limit access to specific hosts. Comment out the
jrun.subnet.restriction parameter and set the jrun.trusted.hosts to
the IP address of your web server, e.g. 10.1.0.54.
Forcing all JRun processes/services to listen on a single
interface isn't difficult, but it does require modifying quite a
few configuration files by hand. If you need assistance with that,
I can elaborate.
Configuring the JRun module under Apache is pretty
straightforward. If you're not using virtual hosts, it's very
simple. If you are using virtual hosts, it's still simple, but your
JRun configuration can be virtual host-specific.
On your Apache server, you'll want to create a directory
structure for the JRun module. I'll assume
/opt/jrun/lib/wsconfig/1, but you can use anything you want. Once
the directory structure is created, extract the appropriate JRun
module from wsconfig.jar to the new directory. You're most likely
interested in the Apache 2.0 module,
wsconfig.jar/connectors/apache/intel-linux/prebuilt/mod_jrun20.so.
Let's assume you've extracted the module to
/opt/jrun/lib/wsconfig/1/mod_jrun20.so. Your Apache service account
should have read, write, and execute permissions on the
/opt/jrun/lib/wsconfig/1 directory.
The JRun module configuration is normally appended to your
current httpd.conf file by wsconfig. Here's a sample configuration:
LoadModule jrun_module
"/opt/jrun/lib/wsconfig/1/mod_jrun20.so"
<IfModule mod_jrun20.c>
JRunConfig Verbose false
JRunConfig Apialloc false
JRunConfig Ssl false
JRunConfig Ignoresuffixmap false
JRunConfig Serverstore
"/opt/jrun/lib/wsconfig/1/jrunserver.store"
JRunConfig Bootstrap 10.1.0.70:51000
#JRunConfig Errorurl <optionally redirect to this URL on
errors>
#JRunConfig ProxyRetryInterval 600
#JRunConfig ConnectTimeout 30
#JRunConfig RecvTimeout 30
#JRunConfig SendTimeout 30
AddHandler jrun-handler .jsp .jws .cfm .cfml .cfc .cfr
.cfswf
</IfModule>
You may also want to update your DirectoryIndex directive
with an appropriate index page, e.g. index.cfm.
After the first request to a page handled by the JRun module
is received, the module will query the boostrap server,
10.1.0.70:51000, for a list of cluster peers. If you've configured
your cluster correctly, a line similar to following will be written
to /opt/jrun/lib/wsconfig/1/jrunserver.store:
proxyservers=10.1.0.70:51000;10.1.0.71:51000
You can create/edit this file manually as well.
Unfortunately, the bootstrap option only accepts one server. If
your bootstrap server is down, the JRun module will use the values
in jrunserver.store directly, if the file exists.
Here's a complete list of JRun module options:
metrics *
debugger *
ssl *
verbose
traceflags
serverstore
bootstrap
errorurl
apialloc
ignoresuffixmap
proxyretryinterval
connecttimeout
recvtimeout
sendtimeout
sslcalist
Options flagged with an asterisk can only be configured at
the Apache server level. All other options can be configured at the
server level and/or the virtual host level. The usage of these
options is in the JRun documentation, and the JRun module source
code is included in wsconfig.jar. Keep in mind that versions of the
JRun module shipped prior to ColdFusion 8 were coded to assign the
connecttimeout and sendtimeout options to the socket connection
timeout. Whichever option appeared last in your configuration ended
up as the final value. This has been fixed in ColdFusion 8 and
presumably the next release of the JRun updater.
I think that's a good start. If you need more information or
can't find what you need in the JRun or ColdFusion documentation,
let me know.
If you're looking for resiliency, I highly recommend
expanding your configuration to include a second web server and a
hardware load-balancer (preferably one that supports redudancy via
multiple paths and devices, e.g. devices from Cisco, F5, or Foundry
Networks). Often, however, running Apache on the ColdFusion
server(s) provides adequate performance, and round-robin DNS
records coupled with the ability to update DNS quickly in the event
of a failure may be all you need for load-balancing and
failover.

Web Proxy Server Load Balancing

I deployed Sun Jave Web Proxy Server 4.0 as a Reverse Proxy. I would also like to use it as a load balancer. As per the instructions, I configured the obj.conf file as shown below
Route fn="set-origin-server" server="https://xx.xx.xx.xx" server="https:yy.yy.yy.yy" sticky-cookie="JSESSIONID" sticky-param="jsessionid" route-hdr="Proxy-jroute" route-cookie="JROUTE" rewrite-host="true" rewrite-location="true" rewrite-content-location="true"
But, it is not doing load balancing. It always sends to the first server (xx.xx.xx.xx). I guess that is because I used mapping as follows:
NameTrans fn="reverse-map" from="https:xx.xx.xx.xx" to="https://server.net" rewrite-location="true" rewrite-content-location="true"
NameTrans fn="redirect" from="http://server" url="https://xx.xx.xx.xx"
NameTrans fn="map" from="https://server" to="https://xx.xx.xx.xx" rewrite-host="true" name="pa-server-farm1" NameTrans fn="map" from="/" to="https://xx.xx.xx.xx" rewrite-host="true" name="pa-server-farm1"PathCheck fn="url-check"ObjectType fn="block-ip"
ObjectType fn="cache-enable" cache-auth="1" cache-https="1" query-maxlen="0" min-size="0" Service fn="proxy-retrieve"
I don't understand how routing and mapping work togother. Any help in this regard is appreciated.

Motor,
the following is from the Web Proxy Sever Administration guide. Please, check the last paragraph for the explanation. Any how, the problem is simple. I am using the Proxy Server as the Reverse proxy. And at the same time, I would like to use two origin servers (for load balancing) instead of one. How do I make both load balancing and reverse proxy functions work together?
Thanks
To Create Regular or Reverse Mapping
Access the Server Manager, and click the URLs tab.
Click the Create Mapping link.
The Create Mapping page is displayed.
In the page that appears, provide the source prefix and source destination for the regular mapping,
for example,
Source prefix: http://proxy.site.com
Source destination: http://http.site.com/
Click OK.
Return to the page and create the reverse mapping, for example,
Reverse mapping:
Source prefix: http://http.site.com/
Source destination: http://proxy.site.com/
To make the change, click OK.
Once you click the OK button, the proxy server adds one or more additional mappings. To see the mappings, click the lView/Edit Mappings link. Additional mappings would be in the following format:
from: /
to: http://http.site.com/
These additional automatic mappings are for users who connect to the reverse proxy as a normal server. The first mapping is to catch users connecting to the reverse proxy as a regular proxy. The �/� mapping is added only if the user doesn't change the contents of the Map Source Prefix text box provided automatically by the Administration GUI. Depending on the setup, usually the second mapping is the only one required, but the extra mapping does not cause problems in the proxy.

Web Dispatcher - Reverse Proxy and Load Balancing

I'm finding limited docs on Web Dispatcher with regard to reverse proxy and load balancing. Are you aware of some recent presentations or docs in this area? The info on help.sap.com is not what I'm looking for.
Thanks.

Hi,
best thing is that you look at your scenarios and test the web dispatcher against each of it, like:
- SSL
- Portal only
- Web Dynpro ABAP / Java
- BSP
- Different backend systems like SRM, MDM
- Several backends with 1 Web Dispatcher
After getting a list of use cases that you can test quite easily (installation of Web Dispatcher is done fast and can be done on a local PC), you can contact SAP Support and ask them about the specific problems and questions you encountered. This way, you'll get the official answer, sometimes they will even inform you about "secret" parameters and options.
As of the reverse proxy functionality: there are several version of Web Dispatcher available that differ from the functionality offered. The latest version - 7.2 - is the one that offers the most, i.e. allows you to create rewrite rules like Apache.
SAP Note 908097 - SAP Web Dispatcher: Released releases and applying patches
br,
Tobias

Some confusion about Web Cache clustering for load balancing

I have 4 Windows 2003 identical machines having OAS 10g installed with Web Cache (Same Passwords and Oracle Home) . I want to utilize them for load-balancing using Microsoft Network Load-balancing. I followed the Note: 259208.1 till step#10. Now we have virtual machine "IASPROD" for all other nodes {IASPROD1,IASPROD2,IASPROD3,IASPROD4 } I am able to logon to Web Cache manager from all nodes separately.
On Node-1 I added all nodes entries in " Origin Server " having routed "Enabled " for all of them. Same I did added in Site-Definitions and gave alias hostname as "IASPROD" which is virtual server.
Priority =1
Site Hostname =iasprod1.domain Port = 80
Policy = Unrestricted
Origin Server Hostnames , port,proxy
iasprod1.domain 7778 No
iasprod2.domain 7778 No
iasprod3.domain 7778 No
iasprod4.domain 7778 No
I have couple of questions might be very basic but as I am configuring very first time.
1. How do I access all the machines through virtual name as stated above ? I tried but not working.
2. This cluster setup should be repeated for all Nodes or for only node-1.
3. If for only Node-1 than what will heppen in case of Node-1 goes down.
4. How can I verify Load-balancing is working ?
If you guyz can guide me than I'll be very greatful.

One more addition Database is on AIX (9.2.0.4)

SSP5: Using multiple JVM for load balance performance?

Sun 12 MAY 2002
Apps 11.0.3
SSP5 patchset I
HP UX 11.0
db 8.1.7.2 (64-bit)
Load 60 concurrent sessions, each spawning 2.5 - 3 http connections.
CPU 3:750Mhz
RAM 8G
Is anybody using multiple JVM for load balance?
What is your ratio of JVM to concurrent iP sessions?
Are you running Apache/Jserv on a server with any other applications, or is Apache by itself?
If you are not using JVM, how many httpd processes do you get before Apache implodes? We stopped in the water at 90 httpd processes, but performance degraded starting at 70 sessions.
Thx - Don

Using Web Cache to load balance servlet-based Forms (6i and 9i) is unofficially supported. I say "unofficially" because we have actual customers doing it and getting support, but the 2 development teams (Forms and Web Cache) haven't actually done any integration testing of this sort of configuration yet. For your case, please contact your Support rep and ask what was done to use Web Cache as a load balancer for Forms6i at METRO in Germany. The Forms product managemment team is writing up a white paper to describe how to do it, but until then, you'll need to go through Support. Please contact me if you want more information.

Setting up the Apache HTTP Plugin for several BEA Servers

Hey together,
i would like to setup the apache http plugin for several bea-servers.
I am running apache 1.x on my hp-ux system. There are 2 bea-server-domains on this box and both should be proxied by the plugin simultaneously.
As far as i know it isn't possible to run 2 or more instances of the apache webserver. I heard of virtualhosts, maybe i should try this one out.
Somebody knows how to deal with this problem or does any1 know if virtualhosts could cope with my needs?
Thanks in advance

Ok here i am again and i'm stuck. Here my wishes again:
there are 2 weblogic-instances (domains) running on a machine xxx, instance A listening on port 8041, instance B listening on port 8051. I want to configure apache virtualhosts in combination with weblogic plugins, so that request with /ld will be sent to instance A while requests with /ldd will be sent to instance B. Both are no clusters. Therefore i tried it with the following configuration (httpd.conf):
<VirtualHost xxx:8080>
     DocumentRoot "/opt/hpws/apache/htdocs"
     ServerName xxx:8080
     <IfModule mod_weblogic.c>
     WebLogicHost xxx
     WebLogicPort 8041
     #MatchExpression *
     #PathPrepend=/test2
     </IfModule>
     <Location /ld>
     SetHandler weblogic-handler
     PathTrim /ld
     </Location>
</VirtualHost>
# VirtualHost2 = xxx:8090
<VirtualHost xxx:8090>
     DocumentRoot "/opt/hpws/apache/htdocs"
     ServerName xxx:8090
     <IfModule mod_weblogic.c>
     WebLogicHost xxx
     WebLogicPort 8051
     #MatchExpression *
     #PathPrepend=/test2
     </IfModule>
     <Location /ldd>
     SetHandler weblogic-handler
     PathTrim /ldd
     </Location>
Doesnt really work. Can some1 help please?
Thanks

Cluster Apex MS's across multiple nodes for load balancing?

Can Cluster Apex MS's across multiple nodes for load balancing? If Yes/No, any supportive doc's will be much appreciated.
Here is what I did ..........
I tried multiple MS's on different nodes for Apex Domain (clustered)
Deployed apex.war, i.war with targets pointing to cluster.
Apex listener techstack is shared filesystem $HOME/apex, where apex-config.xml and bdb are available
Anyone of the MS's whichever started up first is locking up bdb and 500 server shows up when internal workspace is being launched with host specific url, where as it works fine for the host which actually locked up bdb (first MS that was started)
2nd MS shows errors as below in log files ..
Caused By: com.sleepycat.je.EnvironmentLockedException: (JE 4.0.103)$HOME/apex/bdb The environment cannot be locked for single writer access. ENV_LOCKED: The je.lck file could not be locked. Environment is invalid and must be closed.
Its expected behavior until here .....
++++ I tried something to get it working ++++
Whilst both MS's are up and running, delete $HOME/apex/bdb but let apex-config,xml be as it is...now the internal workspace urls for both hosts work fine. I logged into host specific urls and navigated, created/edited users.,etc and it is all looking good but it did not create new bdb directory under $HOME/apex ...!!
Having said its working fine, the same issue repeats after the MS's bounce. So I did put a command line to delete bdb dir once the MS comes up to avoid the issue but really not sure if this is the right way at all?
Geek's ...awaiting your advice!!

Hey there,
I managed to fulfill my requirement..
If its a cluster on same machine or across machines, this should work
1. Login to machine, cd $DOMAIN_HOME
2. mkdir -p Apex_lsn_config/AdminServer Apex_lsn_config/<MS1> Apex_lsn_config/<MS2> # MS1 and MS2 are the Managed Server names as appropriate
#If you are planning for cluster spawning MS's across machines, make sure you create the dir's on step 2 for each machine respectively. (in my case $DOMAIN_HOME is not shared)
3. Copy apex-config.xml from the /tmp/apex or whatever location you have it currently to Apex_lsn_config/<MS1> Apex_lsn_config/<MS2>
4. cd $DOMAIN_HOME/bin; cp -p SetDomainEnv.sh SetDomainEnv.sh.orig #Backup the file
5. Append -Djava.io.tmpdir in SetDomainEnv.sh as below for JAVA_OPTIONS # Do it on both machine if you are not sharing DOMAIN_HOME and planning cluster across machines
-Djava.io.tmpdir=$DOMAIN_HOME/APEX_CONFIG/${SERVER_NAME}
Hint: Search for "iterativeDev" and append the same line with -Djava.jo.tmpdir
6. Modify "java.io.tmpdir" from the web.xml file of apex.war as below and re-deploy the war
<context-param>
<param-name>config.dir</param-name>
<param-value>${java.io.tmpdir}</param-value>
</context-param>
7. Bounce Weblogic Admin and Manged Servers. Make sure to tail the Managed Server log to see apex-config.xml is picked from the new location.
8. Brew a Coffee for yourself :)
- You find the instructions on creating a cluster from weblogic documentation, the steps mentioned above are only to overcome the bdb locking issue whilst creating a cluster.
Did it help?
Edited by: Oratime on Mar 25, 2013 2:44 AM

Round robin DNS for load balancing between multiple network adapters (Xserve)

I'm attempting to use 'round robin' DNS to load balance between the two ethernet adapters of an Xserve.
Both ethernet adapters are connected to the same LAN and have static IP addresses of 192.168.2.250 and 192.168.2.251.
The DNS zone for the server's local domain/host (macserver.private) has a machine record with both IP addresses (set up in the Lion Server UI).
Having read up on round robin DNS, I would have expected DNS requests for 'macserver.private' to be answered with the two IP addresses ordered at random, achiving my aim of requests being served at random via each ethernet adapter.
However this doesn't seem to be the case. Doing a 'nslookup' from any of the network clients results in the two IP addresses being listed in the same order everytime. And pinging 'macserver.private' only ever results in a response from the same address.
Does anyone know why this is the case? Does Lion Server use a non-standard DNS configuration? Are there any additional settings I need to configure in Lion's DNS server to make adopt a round robin approach to responding to requests?
Thanks in advance for any help!

Be careful what you wish for
Round Robin DNS is rarely the best option for 'load balancing'. At the very least it's subject to caching at various point on the network - even at the client side, once the client looks up the address it will cache that response - this means that subsequent lookups may be served from the client's cache and not refer back to the server. Therfore any given client will always see the same address until the cache expires.
I suspect this is what you're seeing.
You can minimize this by setting a lower TTL on the records. This should result in the response being cached for a shorter period, meaning the client will make more requests to the server, with a higher change of using the 'other' address.
However, you're also going to run into issues with the server having two interfaces/addresses in the same LAN. This isn't recommended.
As Jonathon mentioned, you may be better off just bonding the two interfaces. This will provide an automatic level of dynamic load balancing without the latency of DNS caches, as well as automatic failover should one link fail (as opposed to round robin DNS which will cause 50% of requests to fail until the client cache expires and a new lookup is performed (and, even then, there's still a chance the client will try to use the failed link).

Windows Event Collector - Built-in options for load balancing and high availability ?

Hello,
I have a working collector. config is source initiated, and pushed by GPO.
I would like to deploy a second collector for high availability and load balancing. What are the available options ? I have not found any guidance on TechNet articles.
As a low cost option, is it fine to simply start using DNS round-robin with a common alias for both servers pushed as a collector name through GPO ?
In my GPO Policy, if I individually declare both servers, events are forwarded twice, once for each server. Indeed it does cover high availability, but not really optimized.
Thanks for your help.

Hi,
>>As a low cost option, is it fine to simply start using DNS round-robin with a common alias for both servers pushed as a collector name through GPO ?
Based on the description, we can utilize DNS round robin to distribute workloads and increase fault tolerance. By default, DNS uses round robin to rotate the order of RR data returned in query answers where multiple RRs of the same type exist for a queried
DNS domain name. This feature provides a simple method for load balancing client use of Web servers and other frequently queried multihomed computers. Besides, by default, DNS will perform round-robin rotation for all RR types.
Regarding DNS round robin, the following article can be referred to for more information.
Configuring round robin
http://technet.microsoft.com/en-us/library/cc787484(v=ws.10).aspx
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Best regards,
Frank Shen

Webdispatcher for Load balancing

Hi All,
We have implemented EP7. The portal is configured to redirect to https.
Now we want to use sapwebdispatcher for load balancing.
We are performing the following steps to configure the sapwebdispatcher
1. uncar the icmadmin.SAR
2. sapwebdisp -bootstrap
The following screen appears:
This bootstrap will perform the following steps:
1. create profile file "sapwebdisp.pfl"for SAP Web Dispatcher (if not already existing)
2. create user for web based administration in file "icmauth.txt"(if not already exisiting)
3. start SAP Web Dispatcher with the created profile
After the bootstrap you can use the web based administration
Generating Profile "sapwebdisp.pfl"
Hostname of Message Server (rdisp/mshost): <hostname>
HTTP Port of Message Server (ms/http_port): 8101
Checking connection to message server...OK
Unique Instance Number for SAP Web Dispatcher (SAPSYSTEM): 38
HTTP port number for SAP Web Dispatcher: 8101
Create configuration for s(mall), m(edium), l(arge) system (default: medium): l
WARNING: Maximum number of sockets supported on this system: 2045
Please check the operating system configuration
Profile "sapwebdisp.pfl" generated
Authentication file "icmauth.txt" generated
Web Administration user is "icmadm" with password "xxxxxxxxx"
Restart sapwebdisp with profile: sapwebdisp.pfl
sapwebdisp started with new pid 14014
Web administration accessible with "http://<hostname>:8101/sap/wdisp/admin/default.html"
SAP Web Dispatcher bootstrap ended (rc=0)
<hostname>47> *** WARNING: Could not start service 8101 for protocol HTTP on host "<hostname>m"(on all adapters)
SAP Web Dispatcher up and operational (pid: 14014) ***
Now, if I use any port other than 8101 for HTTP port number for SAP Web Dispatcher the webdispatcher does not work.
If i use port 8101(which i am using currently) then the webdispatcher does the load balancing however i cannot access the http://<hostname>:8101/sap/wdisp/admin/default.html url
Can anyone help me getting both thigs: load balancing and the webdisp admin page also.
Thanks!!
Regards,
Rohit

Hi Rohit,
this is your Profile File
Generating Profile "sapwebdisp.pfl"
Hostname of Message Server (rdisp/mshost): <hostname>
HTTP Port of Message Server (ms/http_port): 8101
Checking connection to message server...OK
Unique Instance Number for SAP Web Dispatcher (SAPSYSTEM): 38
HTTP port number for SAP Web Dispatcher: 8101
Create configuration for s(mall), m(edium), l(arge) system (default: medium): l
WARNING: Maximum number of sockets supported on this system: 2045
Please check the operating system configuration
Profile "sapwebdisp.pfl" generated
Authentication file "icmauth.txt" generated
Web Administration user is "icmadm" with password "xxxxxxxxx"
Restart sapwebdisp with profile: sapwebdisp.pfl
sapwebdisp started with new pid 14014
Web administration accessible with "http://<hostname>:8101/sap/wdisp/admin/default.html"
You have wrongly configured your HTTP port number for SAP Web Dispatcher make it as 80 by default
Sample Profile File:
Profile generated by sapwebdisp bootstrap
unique instance number
SAPSYSTEM = 1
add default directory settings
DIR_EXECUTABLE = .
DIR_INSTANCE = .
Accessibility of Message Servers
rdisp/mshost = Hostname
ms/http_port = 8101
SAP Web Dispatcher Parameter
wdisp/auto_refresh = 120
wdisp/max_servers = 100
wdisp/shm_attach_mode = 6
configuration for small scenario
icm/max_conn      = 100
icm/max_sockets   = 1024
icm/req_queue_len = 300
icm/min_threads   = 5
icm/max_threads   = 15
mpi/total_size_MB = 20
#maximum number of concurrent connections to one server
wdisp/HTTP/max_pooled_con = 100
wdisp/HTTPS/max_pooled_con = 100
SAP Web Dispatcher Ports
icm/server_port_0 = PROT=HTTP,PORT=80
icm/server_port_1 = PROT=ROUTER,PORT=443
Swapnil

Apache HTTP proxying for load balancing only to a group of non-clustered WL servers

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