Common Misconfigured HP-UX Resources (April 2006)

Common Misconfigured HP-UX Resources
By: Mark Ray, Global Solutions Engineering
Steven Albert, Global Systems Engineering
Jan Weaver, Global Systems Engineering
Overview............................................................................................................................................ 3
The HFS Inode Cache .......................................................................................................................... 4
What is an Inode Cache? ................................................................................................................. 4
The HFS Inode Cache is a Static Cache.............................................................................................. 4
Determining the Memory Cost of the HFS Inode Cache......................................................................... 5
The HFS Inode Cache and the DNLC.................................................................................................. 5
Configuring Your HFS Inode Cache ................................................................................................... 6
The HP-UX Buffer Cache ....................................................................................................................... 7
What is the Buffer Cache? ................................................................................................................ 7
Static Buffer Cache Versus Dynamic Buffer Cache................................................................................ 7
How the Buffer Cache Works ............................................................................................................ 8
Buffer Cache and Memory ................................................................................................................ 9
Buffer Headers ............................................................................................................................. 9
Buffer Cache Hash Table............................................................................................................. 10
Buffer Cache Hash Locks ............................................................................................................. 10
Buffer Cache Address Map and Buffer Cache Virtual Map .............................................................. 10
Advantages of Using the Buffer Cache.............................................................................................. 11
Disadvantages of Using the Buffer Cache.......................................................................................... 12
Bypassing the Buffer Cache............................................................................................................. 14
Buffer Cache Guidelines ................................................................................................................. 15
The JFS Inode Cache.......................................................................................................................... 16
What is an Inode Cache? ............................................................................................................... 16
The JFS Inode Cache is a Dynamic Cache......................................................................................... 17
Maximum Inodes in the JFS Inode Cache .......................................................................................... 17
Determining the Current Number of Inodes in the JFS Inode Cache ...................................................... 18
Determining the Number of Active JFS Inodes in Use .......................................................................... 18
Growing the JFS Inode Cache ......................................................................................................... 18
Shrinking the JFS Inode Cache......................................................................................................... 20
Determining the Memory Cost Associated with each JFS Inode ............................................................ 21
Effects of the Kernel Memory Allocator ............................................................................................. 22
Tuning the Maximum Size of the JFS Inode Cache.............................................................................. 24
Tuning Your System to Use a Static JFS Inode Cache .......................................................................... 25
Summary ...................................................................................................................................... 26