TITLE
    Mac OS: Minimizing Memory Fragmentation
Article ID:
Created:
Modified:
19064
12/14/95
11/17/00

TOPIC

    This article explains what memory fragmentation is, when it is likely to occur, and how to minimize it.


DISCUSSION

    Symptom

    A dialog box appears with the message that there is not enough memory to continue even though you are sure your computer has plenty of memory. At other times, the Largest Unused Block information in the About This Computer window does not change even after quitting an application program.

    Products affected

    • Mac OS 9.0.4 and earlier.

    Solution

    Memory fragmentation is similar to hard disk fragmentation, but files stored on a disk can easily be broken up into fragments if there is not enough contiguous space on a disk. Programs that are loaded in memory, however, cannot be fragmented, and thus need a contiguous area of memory. Your computer may have several unused blocks of memory mixed in with the used blocks of memory, but Mac OS can make only a single unused block available to a program.

    Memory becomes fragmented more frequently if virtual memory is turned off.

    To defragment memory, use one of the following techniques:

    Technique 1


      1. Quit all open applications and desk accessories.

      2. Open the applications you need to use.


    Open applications appear in the Application menu. To quit an application, choose it from the Application menu, and then choose Quit from the File menu. The Largest Unused Block in About This Macintosh increases as more contiguous memory is made available, but it doesn't necessarily increase with each program you quit.

    Technique 2

    Restart your computer.

    To avoid fragmentation again, carefully plan the order in which you open and quit programs:


      1. Open first the applications and desk accessories you are least likely to quit.

      2. Open last the applications and desk accessories you are most likely to quit during a work session.


    By opening and closing applications and desk accessories this way, the memory you free up is contiguous with the rest of the Largest Unused Block. When you quit programs in random order, you are likely to have fragmented memory.

    Other Solutions



Document Information
Product Area: Mac OS System Software
Category: General OS
Sub Category: General Topics
Keywords: ksts

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