# key\_buffer\_size question **URL:** \ **Category:** Other MySQL® Questions\ **Created:** [January 6, 2009, 7:30pm UTC](https://forums.percona.com/t/key-buffer-size-question/1051 "2009-01-06T19:30:27Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Offspring2099](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/offspring2099/32/800_2.png) [@Offspring2099](https://forums.percona.com/u/Offspring2099)\ **Post date:** [January 6, 2009, 7:30pm UTC](https://forums.percona.com/t/key-buffer-size-question/1051/1 "2009-01-06T19:30:27Z")
Hello, Please tell me if I’m wrong, but I thought that one increases the ‘key\_buffer\_size’ so that the system doesn’t page, because this physical memory is now reserved for the buffers. So why is it when I increase the `key_buffer_size` my VM Size in Windows Xp grows proportionally? ---
**Author:** ![MarkRose](https://avatars.discourse-cdn.com/v4/letter/m/85f322/32.png) [@MarkRose](https://forums.percona.com/u/MarkRose)\ **Post date:** [March 21, 2009, 6:55pm UTC](https://forums.percona.com/t/key-buffer-size-question/1051/2 "2009-03-21T18:55:02Z")
The key\_buffer is part of the VM size. Obviously, if you make it bigger, the VM size will be bigger. Remember that MyISAM relies on the OS to cache its data (external to MySQL). The key\_buffer only holds indexes. Windows likes to page a lot to make room for the filesystem cache. It’s kind of a blackbox that only Microsoft knows… ---
**Author:** ![Offspring2099](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/offspring2099/32/800_2.png) [@Offspring2099](https://forums.percona.com/u/Offspring2099)\ **Post date:** [March 21, 2009, 7:44pm UTC](https://forums.percona.com/t/key-buffer-size-question/1051/3 "2009-03-21T19:44:34Z")
Thank you for the reply Mark. I found my answer, I should have posted it. VM Size in windows doesn’t not equal virtual memory. It’s the amount of memory the system has requested, not using.