Hi everyone, i am new to unraid and i am not completely familiar with its current capabilities. I have some experience with old school hardware RAID controllers, but not unRAID.

I currently own 4 24Tb drives, 2 of them full of data, 2 empty. My application is hosting video files that usually get written once, and not modified. As long as i am able to sustain ~100mb/s Sequential Writes or Reads i am good. I don't need big IO or crazy random access. Files are usually accessed by a single session.

I would like to know if its possible to:
1) Create a RAID5 (or equivalent) out of this drives, without having to move that data off those drives to create the Volume.
2) Once the RAID5 is created, would it be possible to keep on adding several drives to expand its capacity (needing a rebuild when this is done)? On the "What is Unraid?" link, it says "This means you can add new drives one at a time as your storage needs grow, without having to reorganize your existing data when you expand your setup." Which leads me to believe this is possible, but i would like to understand how it works and its capabilities.
3) Is it possible to use an SSD, say 2 or 4Tb, as a sort of cache to improve write speeds (assuming this is needed, as my previous experience with RAID5 caused really slow writes)? I read about the cache drives, but still trying to understand how they work so i know if that would apply to my application. Would this be used to move files on the network to the unraid server, and hold it there until you can write it to the RAID5 volume? Or this is mostly meant for multiple read and writes, and work in an incremental way?

Really appreciate your input, and let me know if any other details of my application would help with getting to an answer. Regards

Edited April 26Apr 26 by Coyote_ar

Which filesystem are the full drives using?

On 4/26/2026 at 6:33 AM, JorgeB said:

Which filesystem are the full drives using?

Thanks for your response, and sorry for the delay replying. The 2 Disks currently have 2 NTFS volumes. But i don't think it would be a problem to get those other 2 empty disks and create new volumes in whatever file system is most convenient to make this operation.
When on point 1 i said doing it without moving data away from those drives, that is not a proper description. My real requirement would be not moving it away to some other storage aside from my current local hardware. Juggling between this 4 drives wouldn't be an issue.

Regards

Maybe this can clear up what unRAID is.

Unraid can mount NTFS drives, but NTFS support in Linux is rather limited, especially if it needs to repair the filesystem. My recommendation is to format the two empty drives with a Linux filesystem,m, default is XFS, then move the data from the NTFS disks there (this can be done with all the disks locally in Unraid),) and then also reformat them.

23 hours ago, Veah said:

Maybe this can clear up what unRAID is.

That was very helpful, thanks.

23 hours ago, JorgeB said:

Unraid can mount NTFS drives, but NTFS support in Linux is rather limited, especially if it needs to repair the filesystem. My recommendation is to format the two empty drives with a Linux filesystem,m, default is XFS, then move the data from the NTFS disks there (this can be done with all the disks locally in Unraid),) and then also reformat them.

Yes i think this will be the best path.