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Monday, March 17, 2008

WebSphere chatter - Ed Mccarthy

Assuming this environment is built for the customer, one thing to keep in mind, is that when you have such an environment, it will consume CPU even when not processing requests. This occurs because a WebSphere env is "chatty", in that different parts of the software components are always chatting to each other. For example the Load Balancers are sending ping requests to WebSeal every seven seconds by default, to check if WebSEAL is still up, plus they send HTTP HEAD requests to also check if WebSEAL is up. WebSEAL is also sending HTTP HEAD requests to WebSphere to check if WebSphere is up. Within a WebSphere ND cell, the DMGR is chatting to the Node Agents to check it is up, the Node Agents is chatting to the servers.

So in an environment where no requests are being processed, the customer may well see more CPU being used then they expect. The customer might think that CPU should be virtually zero when no requests are being processed, but this wont be the case. How much CPU will be used on the proposed config is hard to say, but you should be aware this will happen, since the customer will no doubt notice it as well. For the dev/test and prod envs, you may see one third to one half of an IFL being used even when the system is processing no requests. However you cannot avoid this, since if you want failover capability etc, then you need all this even to support an env where the expected workload is one request a second.

posted by OttoKee  # 12:18 AM

Monday, March 03, 2008

Power6
Power6 dual-core processor will run between 4GHz and 5GHz and processors ran as fast as about 5.8GHz without exceeding 85 degrees Celsius. For blade servers, Power6 will run closer to 4GHz than 5GHz. Power6 employs several power-saving techniques; low-power idle mode called a "nap" that can cut power consumption by 30 percent to 35% when idle and 10% during load, dynamically adjusts processor frequency and voltage, lowering both when possible to cut power, customers can set a "cap" on maximum power consumption for a server. Power6 allows up to 64-chip support for servers. The first Power6 systems, lower-end models, are due to arrive midway through 2007. Power6 has multiple mechanisms to catch data transmission errors and introduces a feature called instruction retry from the gold standard of reliabilities, IBM's mainframe servers. IBM plans to introduce a quad-chip module (QCM) that combines two chips in one package that fits into a single processor socket.

posted by OttoKee  # 7:18 PM

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