AIX Tip of the Week

AIX Tip of the Week: Server Consolidation Technical Considerations

Audience: IT Managers and Administrators

Date: August 20, 1999

Consolidating servers involves multiple considerations, covering business needs, financial benefits, political boundaries, and technical realities. This tip lists some of the technical considerations, which I've grouped into four general categories:

Software Compatibility: The applications, database, utilities, and operating system must be mutually compatible. Consider the stability of each application and its impact on the other applications. Exclude applications that are unstable or require system reboots to fix problems. Rebooting is not an option on a consolidated server. Similarly, rebooting is not an option to change/tune/update the server operating system. So select an operating system like AIX, that has a dynamic kernel that can be managed without rebooting.

Data Content: Consolidate data by type (accounting, HR, sales, etc. and by the database engine (Oracle, Informix, Sybase, DB2, etc. Consolidating data by type simplifies application programming and systems management. Consolidating by database engine lowers costs by reducing the number of licenses.

Network Bandwidth, Protocol: The local area network and server's network adapters must have sufficient network bandwidth to accommodate the increased traffic after consolidation. To simplify systems management, consolidate applications by the network protocol they use (TCP/IP, SNA, Novell, Netbios, etc).

Service Level: This includes performance and availability objectives, covering end user response time, batch windows, maintenance windows, system availability, and recovery time after an outage. In general, it is best to combine applications that stress different system components (i.e. CPU, Disk, Network, Memory), or those that have peak loads at different times of day. Separate applications that contend for the same system resources, such as database engines.

These above considerations are not absolute because every situation is different. Use your best judgment to select the factors most relevant to your situation. If a more detailed approach is required, contact your local vendor. Many have consolidation services. For example, IBM has dedicated server consolidation teams. They use a sophisticated methodology called ALIGN, to identify consolidation opportunities, map application compatibility, size the network requirements as well as cost justify the final solution. Contact your local IBM server consolidation team for more information.

Coming in AIX 4.3.3, (September 15, 1999) will be several features that enhance the RS/6000 server consolidation capabilities. One of these features is workload management which allows the administrator to allocate system resources to specific jobs in increments as small as one percent. This allows the administrator to mix jobs, and ensure critical applications are not impacted by lower priority jobs during peak demand. The workload management functions will be included with the base AIX operating system and will can be managed via WebSM, smit, shell scripts or new AIX commands.