Hitchhiker's Guide to Openbsd

"Write fatigue": Much has been written about the finite number of times an individual flash cell can be 
rewritten before failure. Practically speaking, however, there are many ways a flash device can fail, write 
fatigue is just one of them. Modern flash devices will verify writes, and in the event of failure, will 
automatically remap the failed sectors with one of the many spare sectors. Most users with most flash 
devices will not have to worry about "write fatigue". You would probably experience more down time due 
to failure of "clever" tricks done to avoid writing to the flash drive than you will by just using the drives as 
read-write media. 
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Reliability: The fact that flash media has no moving parts has prompted many people to assume the flash 
media is inherently more reliable than hard disks. It is not wise to assume that switching to flash means 
you don't need to worry about data loss or drive failure. People have reported considerable variation in 
flash media quality, it is probably best to consider flash storage as a silent and low-power alternative to 
disk rather than a failure-free storage media. 
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Creating a bootable USB flash drive: While a USB device can only be booted on a machine which can 
boot from USB drives, it can be created on any machine with supported USB hardware. You will, of 
course, be unable to test your work until you can get to a USB bootable system. 
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Going from IDE to USB interfaces: Since flash media can be readable and writable through USB, IDE 
and other adapters, you can create bootable media with one type of adapter but maintain or use it with 
another type of adapter. 
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Mixing OpenBSD and other partitions on one device: OpenBSD treats the flash disk as any other disk 
so one can use 
fdisk(8)
to partition a flash device, as you would any hard disk. You can then have 
OpenBSD file systems on one partition, and use another partition for another file system, for example, 
FAT32. However, not all OSs treat USB devices as "equals". Windows, at least, will not attempt to use or 
create a partition that doesn't start at the beginning of the device, nor will the Windows partitioning tools 
allow you to partition the disk, though it will respect existing partitions. So, if you wish to create a USB 
flash drive that is bootable with OpenBSD, but also functions as a FAT32-capable device on other OSs, 
you would want to do something like this: 
1. Partition the media with OpenBSD's fdisk, creating a partition of the type you desire for Windows 
to use at the beginning of the disk, and an OpenBSD partition at the end of the disk. 
2. Install OpenBSD as normal to the OpenBSD fdisk partition, don't forget to flag the OpenBSD