Review:

I have been talking about the journalized file system of AIX for some time, and there is really nothing more to be said. I happened to encounter a “page space” failure during my shift today, so I took this opportunity to talk about page space with you. For those of you who are interested in AIX journaling file systems, check out my other article, logical Blocks and Fragments for AIX Journaling File Systems, Creating journaling File Systems for AIX Journaling File Systems.

To know the new:

Page space is a virtual memory that holds programs and data that are not currently being used, while programs and data that are currently being accessed reside in memory. Why use page space? The reasons are listed below.

Page space is a virtual memory, you may think it is not easy to understand, let’s give an example to help you understand it. Suppose the company now provides two rooms for interviews, the interview room called “real memory” and the waiting room called “page space.” There will be 10 interviewers, one at a time. At first everyone is waiting in the waiting room for the interview, which is the equivalent of an inactive program or data in the page space. When the interview begins, the interviewer enters the interview room to begin the interview, which is equivalent to the application and data running in the actual memory. When the first interviewer finishes the interview, he/she returns to the waiting room to wait for the result, while the second interviewer enters the interview room, which is equivalent to moving the programs and data that are not running in the real memory to the page space, so as to free up enough real memory space for the current running programs to use. In the real memory (the interview room), not all programs are running and not all data is being accessed. Only part of programs and data (the person being interviewed) are active. If there is not enough real memory space, Programs that are not currently running and data that is not currently in use (people who have completed interviews) can be moved into the page space (waiting room), freeing up enough real memory space to be used by the currently running program, so that the page space is in effect a back-up of real memory. Although the page space is the second memory, but the program and data in the page space are not active, to run these programs and access these data, they must be moved to the real memory, can be run or access, so the page space is not a substitute for real memory.

I hope this is all clear. Haha, the next post is about creating/deleting page Spaces on AIX.