I have two tier system.
WebSphere Application Server.
The first tier is called "Web" but is a regular ApplicationServer Cluster.
The second tier is called "App" and is a regular ApplicationServer Cluster.
I invoke some EJBs using rmi:iiop:
but the distribution of requests in the App isn't even.
I would like to have the effect of a load balancer.
Is that possible?
By the way, I don't have weights (other than default == 2), so I don't understand why a certain App server is given most of the requests.
Thank you.
Here you can find a very nice presentation about this issue:
Workload Management (WLM) Overview and Problem Determination
What you see is probably due to "Prefer Local" which sends the request to the server resides on the same hostname.
Usually its a good idea but you can turn it off of course.
Related
You could say I am a fan of the Realm Mobile Platform. I'm using it and it seems to be working well.
However I am confused with how to operate it going to production. It seems to be deployed only to one server, and even the professional and enterprise editions are working on my single server.
Assuming Realm have thought of this (as Enterprise edition supports 'enterprise scaling) - how does this work if all clients point to my owned server URL?
Another question is how to monitor the load on that server.
Thanks!
The Professional Edition and the Enterprise Edition emit statsd compatible metrics which allow you to track the usage and load on each node in a Realm Object Server cluster. These metrics are also used internally inside the cluster in order to display statistics about the health of the cluster.
We are obviously still adding metrics as we understand more about our customer's use-cases, and fine-tuning the ones that we have.
With regards to the way the clustering works, we are currently implementing this according to an iterative process, where we add more and more features, and more and more resilience to the system with every passing day.
Basically, we have a logical load balancer process, which receives the incoming client connections, and then dispatches that to a node inside the cluster. This logical load balancer can be HA'd and LB'd itself as well, just like you would any regular WS connection handler. Handling many connections these days is easy. It's handling the quadratic merge algorithms that is expensive on the Realm Object Server, which is why the clustering is required for deployments at scale.
I am new to oracle coherence
Basically we have some data and we wanted some java/bpel webservice to get those data from coherence cache instead of database. [we are planning to load all those data to cache server]
So we have below questions before we start this solution.
Webservice we are planning to start is going to be just java would be fine.
And all operations are reading only.
Question
1. IS it Coherence needs to be stand alone server ? (down load from oracle and install it separately and run the default cacheserver) ?
2.If so we are planning to do the pre loading of data from database to cache server by using code ? i hope thas possible ? Any pointers would be helpful ?
3.How does the webservice connect with Coherence server if webservice running in different nmachine vs coherence server running ?
(OR)
Is it mandatory that webservice and coherence should run in the same machine ?
If webservice can run in different machine how does the webservice code connects to coherence server (any code sample , url would be helpful) ?
Also what is that coherence comes with weblogic ? Is it not fit for our applications design i assume ?!!!! then what type of solution we go for weblogic with coherence ?
FYI : Our goal is simple we want to store the data in cache server and have our new webservice to retrieve the data from Cache servere instead of database(because v are planning to avoid database trip )
Well, you questions are very open and probably have more than 1 correct answer. I'll try to answer all of them.
First, please take into consideration, that Coherence is not a free tool and you have to pay for a license.
Now, to the answers:
Basically, coherence has 2 parts: proxy and server. The first is the responsible to routing your requests and the second for hosting the data. You can run both together in the same service but this has pros&cons. One Con is that your services will be very loaded and the memory will be shared between two kind of processes. A pro is that is very simple to run.
You can preload all the data from the DB. For that you have to open the Coherence and write your own code. For that, you need to define you own cachestore (look for that keyword in coherence docs) and override the loadAll method.
As far I remember Coherence comes together with Weblogic. That says the license for the one is the license for the second and they come in the same product. I'm not familiar with weblogic, but I suppose is a service of the package. In any case, for connecting to coherence you can refer to Configuring and Managing Coherence Clusters
The coherence services can run in different machines, in different network and even in different places of the world if you want. Each, proxy or server, consumer and DB, could be in a different network. Everything can be configured. You have to say you weblogic server where the coherence proxy will be, you'll set in the coherence proxy/server the addresses of them and you'll configure your coherence server for finding out his database by configuration. Is a bit complicated to explain everything here.
I think I answered before.
Just take into consideration coherence is a very powerful tool but very complicated to operate and to troubleshoot. Consider the pros/cons of accessing directly your DB and think about if you really need it.
If you have specific questions, please don't hesitate. Is a bit complicated to explain everything here since you're trying to set up one of the complicated system I ever seen. But is excellent and I really recommend it.
EDIT:
Basically Coherence is composed by 2 main parts: proxy and server. The names are a bit confusing since both are servers, but the proxy serves to the clients trying to perform cache operations (CRUD) while the "servers" serve to the proxies. Proxy is the responsible for receiving all the requests, processing them and routing them, according to their keys, to the respective server who holds the data or who would be the responsible for holding it if the operation requires a loading act. So the answer to your questions is: YES, you need at least one proxy active in your cluster, otherwise you'll be unable to operate correctly. It can run on one of your machines on into a third one. Is recommended to hold more than 1 proxy for HA purposes and proxies can act as servers as well (by setting the localstorage flag to true). I know, is a bit complicated and I recommend to follow oracle docs.
Essentially, there are 2 types of Coherence installation.
1) Stand-alone installation (without a WebLogic Server in the mix)
2) Managed installation (with Weblogic Server in the mix)
Here are a few characteristics for each of the above
Stand-alone installation (without a WebLogic Server in the mix)
Download the Coherence installation package and install (without any dependency on existing WebLogic or FMW installations)
Setup and Configure the Coherence Servers from the command-line
Administer and Maintain the Coherence Servers from the command-line
Managed installation (with Weblogic Server in the mix)
Utilize the existing installation of Coherence that was installed when WebLogic or FMW was installed
Setup and Configure the Managed Conherence Servers to work with WebLogic server
Administer and Maintain the Managed Coherence Servers via the WebLogic console
Note the key difference in terminology, Coherence Servers (no WL dependency) vs. Managed Coherence Servers (with WL dependency)
I am setting up a virtual environment as a proof of concept with the following architecture:
2 node web farm
2 node SQL active/passive fail-over cluster
2 node BizTalk active/active cluster
The first two are straight forward, now I'm wondering about the BizTalk cluster.
If I followed the same model as setting up SQL (by using the Fail-over cluster manager in windows to create a cluster) I think I would end up with an active/passive cluster.
What makes a BizTalk cluster Active/Active?
Do I need to create a windows cluster first, or do I just install BizTalk on both machines and configure BizTalk appropriately?
Yes, my understanding is that you do need to cluster the OS first.
That said, you can usually avoid the need for clustering unless you need to cluster one of the 'pull' receive handlers like FTP, MSMQ, SAP etc. For everything else IMO it usually makes sense just to add multiple BizTalk servers in a group, and then use NLB for e.g. WCF Receive adapters.
The Rationale is that by running multiple host instances of each 'type' (e.g. 2+ Receive, 2+ Process, 2+ Send, etc), is that you also have the ability to stop and start host instances without any downtime, e.g. for maintenance (patches), application deployment, etc.
The one caveat with the Group approach is that SSO master doesn't failover automatically, although this isn't usually a problem as the other servers will still be able to work from cache.
You can configure a BizTalk Group in multi-computer environment. You can refer to the doc available at MSDN download center for more details. The document specifically has a section titled "Considerations for clustering BizTalk Server in a Multiple Server environment"
You can also additionally configure your BizTalk host as a clustered resource. You can refer to the documentation available at MSDN for more details.
I am working on asp.net (newbie) and I am trying to understand what it means to do "load balancing" for the web site. The website will be used by multiple users and resources (database, web service,..).
If anyone could help me understanding the concept of the load balance for asp.net web site, I would really appreciate it.
Thanks.
One load-balancing-related issue you may want to be aware of at development time: where you store your session state. This MSDN article gives a good overview of your options.
If you implement your asp.net system using "out-of-process" or "sql-server-mode" session state management, that will give you some additional flexibliity later, if you decide to introduce a load-balancer to your deployed system:
Your load balancer needn't handle session affinity. As one poster mentioned above, all modern load-balancers handle it anyway, so this is a minor consideration in any case.
Web-gardens (a sort of IIS/server-implemented load-balancer) REQUIRES use of "out-of-process" or "sql-server-mode" session state management. So if your system is already configured that way, you'll be one step closer to being able to use web-gardens.
What is it?
Load balancing simply refers to distributing a workload between two or more computers. As a concept, it's not unique to asp.net. Although having separate machines for your database and web server could be called "load balancing" it more commonly refers to using multiple machines to serve a single role, such as having multiple web servers.
Should you worry about it? Probably not. Do you already have a performance problem? Are your database and web server on their own machines? If you do find that your server resources are strained, it would probably be easier to scale up (a more powerful single machine) than out (load balancing). These days, a dedicated box can handle a LOT of traffic if your code is decent.
Load Balancing, in the programming sense, does not apply to ASP.NET; it applies to a technique to try to distribute server load across two or more machines, rather than it all being used on one machine. Unless you will have many thousands (millions?) of users, you probably do not need to worry about it.
Check the Wikipedia article for more information.
Load balancing is not specific for any on technology stack be it asp.net, jsp etc. To load balance is to spread the incoming requests to a web site over more than one server. This is typically done with a software or hardware load balancer. The load balancer sits in front of two or more web servers and delegates the incoming traffic. Although this technique is not limited to web servers. Load Balancing
Enjoy!
I've never used it, but an option is IIS Application Request Routing.
IIS Application Request Routing (ARR)
2.0 enables Web server administrators, hosting providers, and Content
Delivery Networks (CDNs) to increase
Web application scalability and
reliability through rule-based
routing, client and host name
affinity, load balancing of HTTP
server requests, and distributed disk
caching
In a typical web server/database scenario, the db is almost always guaranteed to load up the machine first. This is because dealing with storing data requires more resources. Before you even start looking at load balancing your web server, you need to think about how to load balance the database.
Spreading one database across multiple servers is a lot harder than load balancing a web server. One of the techniques that can be used is sharding (or horizontal partitioning). This is where some records are stored on one server, and other records - on another server. For example records with ID 1-900000 are on server 1 and records 900001- are on server 2.
In comparison to DB load balancing, spreading the load across multiple ASP.NET servers is not overly complicated. Most of the session issues can be easily mitigated by using out of process session and/or never talking to Application.Cache directly. Data load balancing on the other hand is hard and requires a lot of planning and trial and error. In most cases, talking to a load balanced DB requires using an ORM which supports it (e.g. NHibernate) or your own Data Access Layer. The reason being is that you need to take out establishing a connection from the code that uses the database, so that the decision which DB to talk to is handled in one place.
the exact solution is to save session into the SQL Server with Stored Procedure. To read session call 'SessionCheck' stored Procedure.
I'd add that it really isn't something to worry about. By the time you need a load balancer, you can probably afford one of the neato newfangled ones with sticky sessions so you don't even have to deal with the session boogeyman.
At one of our client's site we have the following topology of BizTalk 2006 in production environment:
2 BizTalk Runtime servers
1 SQL Server with MsgBox and TrackingDB on it.
One of the runtime servers are dedicated physical server and the another is virtual server, though both have 4 CPUs and 8Gb of memory.
The physical server CPU is hardly in use while the virtual server is always on 50% - 60% of CPU usage.
Is there any way to configure the BizTalk load balancing algorithm in such a way that it would load on one server more than on the other?
Yes and no is the accurate answer :-)
Given one host, with one instance on each server, BizTalk would apply a simple round-robin approach to load balancing; as a service (orchestration or pipeline) is tied to a host the answer would be that for a single service it is not possible to assign more "weight" for a particular server -load would be spread evenly between the instances.
However, if you have multiple services, and it makes sense, you could distribute some of them exclusively to the physical box while some to both; this would mean that the physical box would take more load compare to the virtual one.
Obviously - on a two servers configuration - it does mean you lose redundancy though, a decision I would have not taken lightly so I would recommend against it.
(having said that - you say you have one SQL box, so perhaps redundancy is not a major issue?)
Also, if you're doing HTTP receives, check the donfiguration of your web load balancer. It maybe preferring one server over the other based on its configuration.
Another suggestion would be to disable the host instances on the VM and run primarily off of the physicaL box. If the physical box goes down, set up a MOM alert or such to kick off a script to start up the VMs host instances. We do something like this for FTP receives in our cluster.