Hitchhiker's Guide to Openbsd

14 - Disk Setup
Table of Contents
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14.1 - Disks and Partitions
 
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14.2 - Using OpenBSD's fdisk(8)
 
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14.3 - Using OpenBSD's disklabel(8)
 
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14.4 - Adding extra disks in OpenBSD
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14.5 - How is swap handled?
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14.6 - Soft Updates
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14.7 - How do OpenBSD/i386 and OpenBSD/amd64 boot?
 
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14.8 - What are the issues regarding large drives with OpenBSD?
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14.9 - Installing Bootblocks - i386/amd64 specific
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14.10 - Preparing for disaster: Backing up and Restoring from tape.
 
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14.11 - Mounting disk images in OpenBSD
 
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14.12 - Help! I'm getting errors with IDE DMA!
 
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14.14 - Why does 
df(1)
 tell me I have over 100% of my disk used?
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14.15 - Recovering partitions after deleting the disklabel
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14.16 - Can I access data on filesystems other than FFS?
 
❍
14.16.1 - The partitions are not in my disklabel! What should I do?
 
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14.17 - Can I use a flash memory device with OpenBSD?
❍
14.17.1 - Flash memory as a portable storage device
❍
14.17.2 - Flash memory as bootable storage
 
❍
14.17.3 - How can I make a "Live" bootable USB device?
 
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14.18 - Optimizing disk performance
●
14.19 - Why aren't we using async mounts?
14.1 - Disks and Partitions
The details of setting up disks in OpenBSD vary between platforms, so you should read the installation 
instructions in the 
INSTALL.
file for your 
platform
to determine the specifics for your system. 
Drive identification
http://www.openbsd.org/faq/faq14.html (1 of 34)9/4/2011 10:02:25 AM

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14 - Disk Setup
OpenBSD handles mass storage with two drivers on most platforms, depending upon the normal command set 
that kind of device supports: 
●
wd(4):
 IDE disks (and devices that look like IDE disks, for example, SATA, MFM or ESDI disks, or a 
flash device with an appropriate adapter) attached to a 
wdc(4)
 or 
pciide(4)
 interface. 
●
sd(4):
Devices that utilize SCSI commands, such as SCSI disks attached to a SCSI adapter, USB disks, 
SATA disks attached to an 
ahci(4)
 interface, and disk arrays attached to a RAID controller. 
The first drive of a particular type identified by OpenBSD will be drive '0', the second will be '1', etc. So, the first 
IDE-like disk will be wd0, the third SCSI-like disk will be sd2. If you have two SCSI-like drives and three IDE-
like drives on a system, you would have sd0, sd1, wd0, wd1, and wd2 on that machine. The order is based on the 
order they are found during hardware discovery at boot. There are a few key points to keep in mind: 
●
Drives may not be numbered in the same order as your boot ROM attempts to boot them (i.e., your system 
may attempt to boot what OpenBSD identifies as wd2 or sd1). Sometimes you may be able to change this, 
sometimes not. 
●
Removing or adding a disk may impact the identity of other drives on the system.