Hitchhiker's Guide to Openbsd

14.18 - Optimizing disk performance
Disk performance is a significant factor in the overall speed of your computer. It becomes increasingly important 
when your computer is hosting a multi-user environment (users of all kinds, from those who log-in interactively 
to those who see you as a file-server or a web-server). Data storage constantly needs attention, especially when 
http://www.openbsd.org/faq/faq14.html (32 of 34)9/4/2011 10:02:25 AM

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14 - Disk Setup
your partitions run out of space or when your disks fail. OpenBSD has a few options to increase the speed of your 
disk operations. 
●
Soft Updates
●
Size of the namei() cache
 
14.18.1 - Soft updates
An important tool that can be used to speed up your system is softupdates. One of the slowest operations in the 
traditional BSD file system is updating metainfo (which happens, among other times, when you create or delete 
files and directories). Softupdates attempts to update metainfo in RAM instead of writing to the hard disk each 
and every single metainfo update. Another effect of this is that the metainfo on disk should always be complete, 
although not always up to date. You can read more about softupdates in the 
Softupdates FAQ
 entry. 
14.18.2 - Size of the namei() cache
The name-to-inode translation (a.k.a., namei()) cache controls the speed of pathname to 
inode(5)
translation. A 
reasonable way to derive a value for the cache, should a large number of namei() cache misses be noticed with a 
tool such as 
systat(1)
, is to examine the system's current computed value with 
sysctl(8)
, (which calls this 
parameter "
kern.maxvnodes
") and to increase this value until either the namei() cache hit rate improves or it 
is determined that the system does not benefit substantially from an increase in the size of the namei() cache. 
After the value has been determined, you can set it at system startup time with 
sysctl.conf(5)
.