Frequently Asked Questions

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Is pricing for Unraid OS "one time"? Is there any fee for updates?

Unraid OS registration key pricing reflects a one-time fee for “Unraid OS” and updates are included. Pretty great deal, right?

What happens when my USB fails? Do I have to repurchase my registration key?

If your USB Flash boot device fails, you can transfer your registration key to a new USB Flash device initially at any time, and subsequently using the automated transfer system up to once per year. Here's a link on how to do that: if you need to make such a transfer before a year has elapsed from the previous transfer then you need to contact Limetech by email explaining the circumstances.

Can I transfer my Trial registration key to a new flash device?

No. Trial registrations are only valid on the originally used USB flash device. If you wish to purchase a registration key, you can transfer your Trial configuration to a new flash device and then purchase a registration key, but you cannot continue using a Trial configuration on a new USB flash device.

I need help with a build / system configuration. Where do I go?

For assistance with creating a special build for Unraid OS, we highly advise users to check out our Compulsive Design forum. Our community is fantastic about helping folks create their ultimate Unraid system.

Can you guys recommend any storage controllers (or other hardware) for my build?

It is our general policy to not recommend specific hardware to end-users. There is so much hardware out there to choose from that we couldn't possibly test it all, but thanks to our friendly community, most users have tried almost everything that's out there, so if you need a recommendation, check the forums!

Does Unraid support hardware-based RAID controllers?

While some users have been able to use RAID controllers to present devices to Unraid OS for use, they definitely complicate things when it comes to features and maintenance. Disk temperatures and even some SMART values may not come through correctly when presented through a hardware RAID controller. Therefore we only officially support the use of non-RAID controllers for storage devices. Most RAID storage controllers offer a way to flash the firmware to convert the card into a basic HBA for devices (eliminating the RAID entirely), but you'll have to search for your specific controller to see if that is an option.

Can I use a HASP key within a VM on Unraid? How does that work with multiple VMs?

If the HASP key is a USB dongle, then you can assign it to a single virtual machine at a time. Two VMs cannot be running with concurrent access to the same key. In addition, depending on how the device works, you may need to assign an entire USB controller to the VM for which you want to use the key. You'll need to test this with a Trial license of our software before committing to a purchase because all USB devices can be a bit different in how they work within a VM.

I'm a reseller/OEM that needs to purchase a key on behalf of my customer, how do I do that and receive a proper invoice?

You will need to purchase the registration key the same way as the customer would (from the webGui). However, at checkout you will be presented with three options:

Individual Business/Organization OEM

Select OEM and enter your purchase details, and then also enter your customer name and email address. The purchase will be to you but the key will be in your customer’s name and sent to them. There will also be an invoice download link upon completion.

Troubleshooting and Support

My USB flash has failed and I don't have a backup. How do I restore my configuration?

First and foremost, you'll need to get a new flash device. Remember to get something of quality (Kingston, PNY, Lexar, and SanDisk are a few brands we've had good success with). Second, you'll need to find the e-mail with your registration key for your previous flash device. Last, you'll need to install Unraid on the new flash device, boot it up on your server, and then install the old registration key on the new flash (from the Tools > Registration page). From there you can request and then install a replacement key.

As far as your configuration goes, if you can remember your drive assignments (which disks were assigned to which slots), you should be able to simply re-assign them all and start the array. You may need to reconfigure your shares, users, and other system settings, but your data should be intact.

If you cannot remember your drive assignments, please post on the forum for further assistance (under General Support).

How do I go about getting an extension for my Unraid Trial?

Simple! Simply reboot your server and navigate to the Tools > Registration page. From there you can click to request an extension. Please remember that you are only allotted up to two extensions, each for two weeks. No further extensions can be issued thereafter.

I wish to completely start configuring Unraid OS from scratch. How do I wipe my existing configuration / filesystems and do that?

  1. Ensure there is no data on the system that you require.
  2. Stop the array and shut down the server.
  3. Remove the USB flash device.
  4. Using a Windows or Mac computer, reformat the flash using the USB Flash Creator tool from our website.
  5. Reinstall the flash in the server and boot it up.
  6. Click on the "terminal" icon in the top right corner of the webGui.
  7. From the command line, type this: lsblk
  8. Note all the devices present excluding your USB flash device.
  9. Now for each device in the list (excluding the USB flash device), type the following command: wipefs /dev/sdX (replacing X with the letter of the device from the previous steps). This will remove the filesystem from the device so it can be reformatted by Unraid OS.
  10. Now continue reconfiguring Unraid OS per the normal procedure.

Whenever I shut down my Windows 10 VM with my AMD GPU assigned, if I try to start it again, it doesn't work. What do I do?

This is due to issues with many AMD GPUs not supporting function-level resets. NVIDIA GPUs are recommended as they do not have this problem. A workaround to this issue is to eject the GPU from the VM before shutting it down. You can do this from the bottom right corner in Windows where you would also find any USB devices. Just eject the GPU, then use another machine to shut down the VM from the Unraid webGui. Then when you start it again, it shouldn't have any problems.

How do I pass through my primary GPU to a VM when my CPU doesn't have an integrated graphics device?

This can be a challenge, but luckily our friendly community member SpaceInvaderOne has this covered in a video guide on our forums:

What's the best way to add more storage to a system than the built-in controller supports?

Unraid can easily scale storage across multiple controllers in a system. The controllers must act as standard HBAs and not actual "RAID" controllers. Most RAID controllers offer an option to either flash their firmware or reconfigure the card into a mode to operate this way.

Does Unraid support various RAID types such as RAID1/5/6/10?

Unraid manages storage in two separate buckets: the array and the cache. The array itself uses dedicated parity device(s) similar to a MAID ( The array cannot be configured into traditional RAID methods such as RAID 1/5/6/10.

The cache is created using btrfs. When more than one disk is present, the cache is called a "pool" and is by default configured to use btrfs RAID1, which is a slightly different take than a traditional RAID1. The cache can optionally be configured to use btrfs RAID 5/6/10, but RAID 5/6 on btrfs is still considered unstable, so it isn't recommended for production use.

I'm getting an error registering my flash device: '####-####-####-#############' is already registered to another user. What do I do?

The flash device you are trying to use with Unraid OS doesn't have a unique ID, and therefore is ineligible for registration. Please obtain a different USB flash device for use with Unraid OS. A few brands that work best include SanDisk, Lexar, or PNY.

My system is crashing but my logs don't contain the event. What do I do to obtain support?

Sometimes a hard system crash can prevent you from obtaining vital information in the logs that would help better diagnose the issue. In the event you can't obtain the logs with a remote connection, you'll have to resort to a local one. Attach at least a monitor and keyboard to the server and boot it up into non-GUI mode. Once presented with the login prompt, login as the user 'root' and whatever password you set when you set up the server (if no password was set, leave it blank and press enter again). From the command line now, type the following command:

tail /var/log/syslog -f

This will begin printing the system log to the monitor directly. Now go about using the server as you normally would. When the crash occurs, take a picture of what's visible on the monitor and post it in the support forums. This will hopefully give us some further insight on the issue.

Is there any way to disable the br0 bridge?

Absolutely! Simply navigate to the Tools > Network Settings page to disable network bridging. Note that this will result in differences in behavior for virtual machines (including losing the ability to communicate with the host from a guest).

After upgrading from Unraid 4, I'm getting read access errors when attempting to access files

After upgrading from a release older than 5.0.5, you may need to run the New Permissions utility to restore access to your files. To do this, navigate to the Tools > New Permissions page and click to run that utility. It will take some time to complete, but upon completing, your read-access should be restored.

How do I enable UEFI boot mode if I configured my flash device using the manual method?

Simply remove the dash symbol from the EFI folder on the root of the flash drive and then make sure your motherboard BIOS is configured to boot UEFI.

How do I determine what registration type (Basic, Plus, or Pro) I have?

Simple! Navigate to the Tools > Registration page and you can review your current key type and registration information.

I'm having problems passing through my RTX-class GPU to a virtual machine

Posting in the forums for assistance is always recommended when troubleshooting a VM / pass through problem, but there is something worth noting about these newer devices that are unique compared to previous series cards. These GPUs feature a USB controller built into the GPU. This is quite fortunate as it can be used with a USB hub to then act as a device your Windows VM can interact with more naturally (such as supporting hotplugging USB devices). However, it is recommended that you stub this device to ensure its driver isn't loaded with Unraid OS. To stub the device, perform the following steps:

1. Locate your IOMMU group containing your GPU and its other devices on the Tools > System Devices page.

2. Notate the vendor and product IDs indicated in the brackets. Example:

[10de:1f08] 02:00.0 VGA compatible controller: NVIDIA Corporation Device 1f08 (rev a1)

[10de:10f9] 02:00.1 Audio device: NVIDIA Corporation Device 10f9 (rev a1)

[10de:1ada] 02.00.2 USB controller: NVIDIA Corporation Device 1ada (rev a1)

[10de:1adb] 03:00.3 Serial bus controller [0c80]: NVIDIA Corporation Device 1adb (rev a1)

3. Navigate to the flash device settings page (on the Main tab).

4. Click on the flash device.

5. Edit the Syslinux configuration by adding the following to the append line on the boot mode selected: vfio-pci.ids=[####:####],[####:####]. Example:

append vfio-pci.ids=10de:1ada,10de:1adb initrd=/bzroot,/bzroot-gui

6. Apply the change and reboot your server.

7. Edit or create your VM and you will now see these additional PCI devices available to assign to your VM without manually editing your XML.

Does Unraid have an allocation feature that remembers bad sectors on drives to prevent writes to them?

Hard drives and SSDs use SMART data to keep track of bad sectors and prevent writes. This is the native functionality of the underlying hardware. That said, if a device is showing a large amount of bad sectors / reallocated sectors, replacing it soon may be a good idea. If you're not sure, try posting in our General Support forum including the SMART data for the drive in question and our community can help determine what to do.

I'm having problems with FreeNAS and considering using Unraid, should I?

OF COURSE! It's important to understand that FreeNAS does not use a Linux-based OS, and therefore cannot utilize features such as KVM, or other Linux-specific platform capabilities. If you're having difficulty getting things to work on FreeNAS, Unraid could be a better option.

I currently have an array of devices that are formatted with an MBR-style partition table and I want to convert to GPT. How do I do that?

Any device 2TB or smaller uses an MBR-style partition table.

Any device larger than 2TB uses a GPT-style partition table.

For Unraid OS version 6.8.x and earlier:

 Starting position of partition 1 for any storage device is 32KiB from the start of the device (regardless of whether MBR or GPT).

Starting with Unraid OS 6.9:

 Default starting position of partition 1 for rotational devices is 32KiB from the start of the device (regardless of whether MBR or GPT).
 Default starting position of partition 1 for non-rotational devices is 1MiB from the start of the device (regardless of whether MBR or GPT)

Presuming user has valid parity and he wants to preserve data:

Must first swap out and rebuild Parity. Swap out each data device and rebuild one-by-one.

For this kind of upgrade, we recommend starting in “Maintenance mode” each time to perform the swap and rebuilds. This will ensure the devices are not written during the process. At the end of the process, the original storage device should be intact.

Also highly recommend downloading flash backup: Main/Flash/Flash Backup