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On Wed, Dec 16, 2009 at 06:56:00PM -0600, Leslie Turriff wrote: |
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> As a 30-year veteran of the IBM mainframe programming environment, I can say |
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> with authority that most of the enterprises that use them for |
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> mission-critical business applications (banking, stock-brokerage, etc.) are |
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> running systems that are updated frequently (sometimes daily) and are fully |
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> capable of being shut down and restarted (on purpose :-D ). Yes, some of |
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> them are front-ended with Linux servers; mainframe systems are not well |
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> designed for managing dynamic web traffic, although systems that do not have |
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> to support very high-volume workflows can do it themselves. The last system |
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> that I worked on was only shut down and restarted twice per year, because 90% |
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> of maintenance could be done while it was running (just like Linux), and |
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> because it was not a business-critical system, it was only required to be |
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> available 99.95% of the time. :-) |
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> |
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> The banking and brokerage systems that I first referred to use a more robust |
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> configuration than we did, which is capable of providing services 100% of the |
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> time, much like a Linux cluster system does. IBM calls the |
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> configuration "Parallel Sysplex." Here's an excerpt of their technical |
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> description, from |
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> <http://www-03.ibm.com/systems/z/advantages/pso/sysover.html>: |
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> |
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> 'This "shared data" (as opposed to "shared nothing") approach enables |
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> workloads to be dynamically balanced across all servers in the Parallel |
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> Sysplex cluster. This approach allows critical business applications to take |
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> advantage of the aggregate capacity of multiple servers to help ensure |
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> maximum system throughput and performance during peak processing periods. In |
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> the event of a hardware or software outage, either planned or unplanned, |
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> workloads can be dynamically redirected to available servers thus providing |
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> near continuous application availability. |
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> Another significant and unique advantage of using Parallel Sysplex technology |
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> is the ability to perform hardware and software maintenance and installations |
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> in a nondisruptive manner. Through data sharing and dynamic workload |
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> management, servers can be dynamically removed from or added to the cluster |
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> allowing installation and maintenance activities to be performed while the |
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> remaining systems continue to process work. Furthermore, by adhering to IBM's |
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> software and hardware coexistence policy, software and/or hardware upgrades |
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> can be introduced one system at a time. This capability allows customers to |
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> roll changes through systems at a pace that makes sense for their business. |
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> The ability to perform rolling hardware and software maintenance in a |
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> nondisruptive manner allows business to implement critical business function |
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> and react to rapid growth without affecting customer availability.' |
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> |
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> Respectfully, |
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> |
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> Leslie |
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|
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Leslie, |
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|
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I appreciate you addressing the previous FUD in such a professional manner. |
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-- |
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"Experience is a hard teacher because she gives the test first, the |
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lesson afterward. But properly learned, the lesson forever changes |
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the man." |