Changing the logical-memory block size

You might enhance the managed system performance by manually or automatically changing the logical-memory block size.

About this task

The system kernel uses the memory block size to read and write files. By default, the logical-memory block size is set to Automatic. This setting allows the system to set the logical-memory block size that is based on the physical memory available. You can also manually change the logical-memory block size.

To select a reasonable logical block size for your system, consider both the performance that is wanted and the physical memory size. Use the following guidelines when selecting logical block sizes:

  • On systems with a small amount of memory installed (2 GB or less), a large logical-memory block size results in the firmware taking an excessive amount of memory. Firmware must use at least one logical-memory block. Generally, select the logical-memory block size to be no greater than one eighth the size of the system's physical memory.
  • On systems with a large amount of installed memory, small logical-memory block sizes result in many logical-memory blocks. Because each logical-memory block must be managed during boot, many logical-memory blocks can cause boot performance problems. Generally, limit the number of logical-memory blocks to 8 K or less.
Note: The logical-memory block size can be changed at run time, but the change does not take effect until the system is restarted.
To change logical-memory block size, you must have one of the following authority levels:
  • Administrator
  • Authorized service provider

Procedure

To configure logical-memory block size, complete the following steps:

  1. On the ASMI Welcome pane, specify your user ID and password, and click Log In.
  2. In the navigation area, expand Performance Setup.
  3. Select Logical Memory Block Size.
  4. In the content pane, select the logical-memory block size and click Save settings.