Filter
Top Products
Controlling Memory Utilization of VxFS 3.5 on HP-UX 11i v2
Introduction
Appendix C156
Introduction
VxFS 3.5 resorts to caching objects in memory as a way to improve
performance. Most of the memory consumed by VxFS is used to cache
inodes (in the inode cache) and metadata (in the buffer cache). The sizes
of these caches and the behavior of VxFS are controlled by a set of
tunables. You can tailor the performance of VxFS to meet a variety of
usage scenarios while taking into account variations in machine
configurations via the use of these tunables.
The default settings of these tunables are meant to provide good
performance for typical deployment configurations. However, these
default values can result in the VxFS driver consuming more memory,
especially when the file systems are stressed (under heavy file system
load). For machines low on RAM, these tunables may need to be
manually turned down depending on the expected use of the machine
and the performance required of the file system.
VxFS 3.5 exposes two global tunables, vx_ninode and vx_bc_bufhwm,
that control the size of the inode cache respectively and thereby affect
system memory consumption by the file system driver.
This appendix discusses when and why the sizes of the inode and buffer
caches need to be tuned down from their default values in certain
configurations. The following sections describe these tunables in detail
as well as the effects of changing their default values.