unRAID Server OS

What is unRAID®?

unRAID is software for storing and managing digital files on a mass-storage server.  In more technical terms, unRAID® is an embedded Network Attached Storage (NAS) server operating system.  It was specifically designed for digital media storage (e.g., videos, photos, music, & movies).  It allows you to build an array of hard drives and share the data from those drives across the local network (typically within a house or business).  Importantly, it protects all the data on the drives if one should fail (see how unRAID works here).

Benefits of unRAID® Technology

The advantages of unRAID over traditional RAID storage systems are:

Lower power requirements saves money

Saves money

Traditional RAID systems spin up all of your drives when reading or writing any data because it stripes your data across several drives at once.  unRAID, on the other hand, only spins up the disk you need to access (plus the parity disk) as it saves data to individual drives and boots the operating system from a USB flash device.  As a result, unRAID

  • Uses less power;
  • Runs cooler and quieter; and
  • Saves wear-and-tear on your drives.

Plus you can try it for free!

“I got unRAID for its added protection over RAID5 and its overall cost savings compared to NAS devices. The ease of setup and lack of time spent getting it to just work has been a welcome, unforeseen bonus.” – fitbrit, customer on unRAID Forum

“I love the idea of a controlled spin down and having the root in RAM to save power, heat, as well wear and tear on the drives.” – WeeboTech, customer on unRAID Forum

“I like that unRAID spins down the disks individually — this is just cool. A huge power savings and less noise.” – ljf, customer on unRAID Forum


You can control and know where your files are located

Gives you ultimate control over your storage

In a RAID array or any pooled-storage server with several hard drives, you don’t know which hard drive contains which data, kind of like not knowing which shipping container is on each ship.  Nor do you have control over what data goes where.  And to many, that’s just fine.  Well, as the saying goes, “knowledge is power”.  With unRAID, you not only have the advantage of being able to view all of your drives on one server as “one”, but you also know what is on each drive.


Knowing what is on each drive is a huge benefit because:

  • You can keep all of your most important files on one disk, back it up, and keep a copy at another secure location.  That way you’ll always feel better about your important financial information, wedding video, family pictures, being safe.
  • When a drive does fail, you know how urgent it is to replace.  If it just had some miscellaneous files or was basically empty, you’re not going to drop everything to run down to the nearest computer store to buy another drive.

Worry-free storage

Makes it virtually impossible to lose everything

After spending hundreds of hours capturing, copying and organizing digital media, you should not have to risk losing your time and data to a hard drive failing. Similar to other RAID systems, unRAID enables reconstruction of a single failed hard drive. However

  • In the event of multiple hard drive failures, data loss with unRAID® would be isolated to only those hard drives that failed. In traditional RAID systems, multiple simultaneous hard drive failure can result in complete data loss.  
  • If any hardware component in a RAID system fails – whether it be the motherboard, CPU, RAM, disk controller, power supply, fans, etc. – you won’t be able to access your data as the system locks up until the hardware issue is resolved.  You’re left wondering “is my data still there?”  With unRAID, you have the flexibility in these situations of unplugging your healthy disks and re-inserting into another server or hooking up to a Windows or Linux machine, giving you immediate access to your data.

“I’ve already had reason to say thank you unRAID!  When I came back from vacation, powered up the unRAID box and boom, one drive dead.  Had about 250GB of videos on it.  Luckily, I had just purchased some new drives so, out with the bad, in with the new, rebuild on the fly while being able to watch a show that I know was on the bad drive.  Can’t beat that functionality.” – cmhardwick, customer on unRAID Forum

“I prefer using unRAID® because it’s mature and very reliable. That alone is enough for me to use unRAID® for protecting my data from HDD failure.” unRAID® customer on XBMC Forum

“Many NAS solutions are going to be a challenge to get at the data if they fail.  The unRAID file format is not proprietary, so there are alternatives to reading the data from other operating systems.  If my unRAID motherboard fries, I’m not dead in the water.”  JRS, customer on unRAID Forum

“Recovery is a big deal for me…If you fried a couple of drives in a standard RAID 0.5, etc. setup, you are SOL due to the striping.  Seriously, unRAID is the superior and cheaper way to go.” – vdtruong, customer on unRAID Forum

Mix and match your drives

Allows mixing and matching drives

  • Unlike traditional RAID systems, with unRAID your hard drives don’t need to be the same size or speed. In fact, any combination of IDE/SATA/SAS hard drives and solid state drives may be used.
  • unRAID is largely hardware independent.  With most RAID systems, this is a very big deal if you are faced with a recovery scenario. This is because if any of your hardware fails (e.g., RAID card, motherboard, CPU, RAM, disk controller, disk drives, power supply, etc.), you have to replace with the exact same hardware.  Good luck sourcing this in a hurry as it may be hard to get as well as expensive.  With unRAID, you won’t have to deal with this hassle.

“The fact that I can freely add any size drive, and freely add them one at a time (since I’m not independently wealthy), sealed the deal for me.” – Bigdog66, customer on XMBC Forum

It's easy to add new drives

Lets you add capacity as you need it

  • You can add capacity by simply adding more devices or by upgrading existing ones. 
  • Also, unlike RAID systems, new devices can be added to the server without disturbing the data on the other devices.

“unRAID gives you painless expandability, better fault tolerance, and better fault recovery.” – bubbaQ, customer on XBMC Forum

“Almost all other NAS solutions require more hardware (other than disks) to expand.  Not so with unRAID.” JRS, customer on unRAID Forum

“One of the key reasons I went with unRAID is its simple, upgradable expandability of drives.” – WeeboTech, customer on unRAID Forum

“I looked at Drobo and Buffalo, but really needed a solution that could scale for our photography business, which is why I chose unRAID.” – Tim R., unRAID customer

Take it for a test drive

Try it for free!

  • unRAID Server is freely available for download, so you can take it for a test drive.  Just assemble a basic media server and install unRAID Server onto your own USB Flash device.
  • Unregistered unRAID Server is fully functional, supporting up to 3 storage devices (1 Parity, 2 data).


Find out how unRAID works here.

Back to Top