The FreeNAS® operating system is installed to at least one device that is separate from the storage disks. The device can be a USB stick, SSD, compact flash, or DOM (Disk on Module). Installation to a hard drive is discouraged as that drive is then not available for data storage.
To write the installation file to a USB stick, two USB ports are needed, each with an inserted USB device. One USB stick contains the installer. The other USB stick is the destination for the FreeNAS® installation. Take care to select the correct USB device for the FreeNAS® installation. It is not possible to install FreeNAS® onto the same USB stick containing the installer. After installation, remove the installer USB stick. It might also be necessary to adjust the BIOS configuration to boot from the new FreeNAS® USB stick.
When determining the type and size of the target device where FreeNAS® will be installed, keep these points in mind:
- the bare minimum size is 8 GB. This provides room for the operating system and several boot environments. Since each update creates a boot environment, this is the recommended minimum. 32 GB provides room for more boot environments.
- if you plan to make your own boot environments, budget about 1 GB of storage per boot environment. Consider deleting older boot environments after making sure they are no longer needed. Boot environments can be created and deleted using System → Boot.
- use quality, name-brand USB sticks, as ZFS will quickly reveal errors on cheap, poorly-made sticks.
- for a more reliable boot disk, use two identical devices and select them both during the installation. This will create a mirrored boot device.