* while Pro keys don’t have an attached-device limit, unRAID OS versions have different assignable device limits. See the FAQ section for more information.
Easy! Just download the OS and register for a free 30-day trial to try it before you buy it!
Can I install unRAID to something other than a USB flash device?
No. unRAID is only supported to run from USB flash-based storage devices. No SD card readers, HDDs, nor SSDs are supported for the boot device.
What happens to my registration key if my USB flash device fails?
Don’t worry! You can transfer your registration key to a new flash device up to once per year. See here for instructions on this procedure.
Why do Basic and Plus have attached device limits?
The Basic and Plus keys are intended to provide a lower cost solution for those with smaller servers.
What are “attached devices”?
They refer to the total number of storage devices physically attached to the system before you start the array. This number is in addition to your USB flash device used to boot unRAID (e.g. 4 HDDs + 2 SSDs + unRAID boot device = 6 attached devices).
What are “assignable” devices?
unRAID 6.1.x only allows for up to 25 total assignable devices between the array and the cache (1 parity, 23 data, and 1 cache device). As of unRAID 6.2, that limit is increased to support up to 30 array devices (28 data and 2 parity) and up to 24 cache devices for a grand total of up to 54 assignable devices. Devices beyond the assignable limit can still be utilized directly with other unRAID features such as virtual machines or the unassigned devices plugin.
No. All unRAID registration keys allow full access to the software’s capabilities. The only difference between registration key types is the total number of storage devices you are allowed to have attached to the system before starting the array.
Will I have to pay for upgrades to newer versions of unRAID as they are released?
No. unRAID Server OS registration keys entitle users to all new releases of the OS at no additional cost.
Why can’t I just purchase a key directly from the website?
We want to ensure each customer can boot unRAID OS on their server hardware and are satisfied with the product before purchase. For special orders, please contact email@example.com.
What happened to the previously available AVS 10/4 server and the pre-configured USB flash devices you used to sell?
We are currently out of stock on all of our hardware. We are not resupplying inventory at this time. If you are looking for high-quality, preconfigured unRAID systems, please contact one of our vendor partners in the forums.
How can I move my unRAID Trial config to a new flash device before purchasing a key?
1 – Prepare the new flash device for unRAID (format with FAT32, label with UNRAID in all caps)
2 – Copy all the files from the old flash device to the new flash device
3 – Run the make_bootable script as per the normal setup process
4 – Boot your server using the new flash device
5 – Purchase a registration key from the Tools > Registration page in the webGui
If you haven’t already, download unRAID Server OS from, install it following the steps outlined here, then follow these steps to purchase a registration key:
- Download unRAID Server OS from here.
- Install it by following these instructions.
- Use a web browser and navigate to the web interface (from Windows: http://tower; from Mac: http://tower.local).
- Click on the Tools tab, then click Registration.
- Click Purchase Key, select an edition, and complete the transaction.
- Paste the key link e-mailed to you in the text box on the Registration page and click Install Key.