Hitchhiker's Guide to Openbsd

/usr/X11R6: This is where the X Window system resides. The X binaries, font files, libraries, etc. all are here. 
The only part of X not here is the configuration files. 
●
/usr/local: On a default OpenBSD installation, this mount point/directory is completely empty. It is used for 
locally installed binaries and libraries for local applications. 
●
/usr/src: This directory holds the basic system source files, excluding X and ports. This directory is empty by 
default, you have to load it as detailed in 
FAQ 5
. 
●
/usr/obj: This directory is populated during the build process with the object and binary files. Having this 
directory a separate mount point allows it to be formatted rather than erased file by file, which can be significantly 
faster. 
●
/home: This is where user files go. Having this a separate partition makes it easy to completely reinstall your 
system; simply don't format this partition on reload. 
Some additional thoughts on partitioning: 
●
For your first attempt at an experimentation system, one big 
/
partition and swap may be easiest until you know 
how much space you need. By doing this you will be sacrificing some of the default security features of OpenBSD 
that require separate filesystems for 
/, /tmp, /var, /usr
and 
/home
. However, you probably should not 
be going into production with your first OpenBSD install. 
●
A system exposed to the Internet or other hostile forces should have a separate 
/var
(and maybe even a 
separate 
/var/log
) for logging. 
●
A 
/home
partition can be nice. New version of the OS? Wipe and reload everything else, leave your 
/home
partition untouched. Remember to save a copy of your configuration files, though! 
●
A separate partition for anything which may accumulate a large quantity of files that may need to be deleted can 
be faster to reformat and recreate than to delete. See the 
building by source FAQ
 for an example (
/usr/obj
). 
●
If you wish to rebuild your system from source for any reason, the source will be in 
/usr/src
. If you don't 
make a separate partition for 
/usr/src
, make sure 
/usr
has sufficient space. 
●
A commonly forgotten fact: you do not have to allocate all space on a drive when you set the system up! Since 
you will now find it a challenge to buy a new drive smaller than 100G, it can make sense to leave a chunk of your 
drive unallocated. If you outgrow a partition, you can allocate a new partition from your unused space, 
duplicate
 
your existing partition to the new partition, change 
/etc/fstab
to point to the new partition, remount, you now have 
more space. 
●
If you make your partitions too close to the minimum size required, you will probably regret it later, when it is 
time to upgrade your system. 
●
If you make very large partitions, keep in mind that performing filesystem checks using 
fsck(8)
 requires about 1M 
of RAM per gigabyte of filesystem size, and may be very time-consuming or not even feasible on older, slower 
systems (please also refer to 
this section
). 
●
If you permit users to write to 
/var/www
(i.e., personal web pages), you might wish to put it on a separate