I use qnap primarily for video editing-nothing else and wondering how much free space should i keep on volume for it to function properly?
I have it set up like this:
QuTs OS on 2 SSDs and main RAID-6 12 drive pool 207 TB total space in windows as a separate thick volume. I don’t use snapshot-no dedup and no compression. System has 64gb ram.
Now, how low can I go on 207TB volume in order to avoid issues? Should it be 10% 21TB or can I go as low as 5% for example with 10TB? Any ideas? Mostly i hear 10%, but it depends if you use snapshots and other stuff I bet! I haven’t found a clear guideline for my use case as the NAS is really just for storage.
Somewhere between 5 and 10% is probably fine. I don’t know for sure, that seems like a reasonable amount. 21TB of free space is still a LOT of space, so when you get that large, maybe you can push it closer to the limit.
By the way, your QTS OS is NOT on just your 2 SSDs. It’s spread across all your drives. The two SSDs are your “system” drive but that is not OS. System drive in QNAP world is where apps are installed by default, where QNAP keeps some databases, default folders like “Public”, etc.
Also, understand that a NAS is not a backup. If you aren’t doing snapshots or anything like that, make sure you are backing up all your storage or you may have a lot of tears a some point if multiple drives start failing or something else bad happens…
My OS is QuTS Hero though not QTS (mentioning just in case). We do have daily backups to Lacie D2s so losing data is ok although not preferable as it will take a long time to copy back!)
To better understand your requirements and provide system configuration recommendations, we would like to ask: when your hard drive capacity reaches its final 10% (or 5%), what actions do you typically plan to take?
Continue adding files: Keep storing new data until the drive is completely full.
File editing/processing: Directly edit or process existing files.
Data backup or migration: Move some files to another storage device to free up space on the NAS.
Once say 5 to 10% is reached all writing to volume just stops and we will only read from the volume and not write to it. Once we reach that point we will get a new additional NAS to continue work and editing (read/write) on the new NAS.
Regarding your specific usage, if your primary application is simply for data storage and retrieval, and you do not plan to run many high-load programs on the NAS (such as multiple VMs, heavy container apps, or intensive video transcoding), then theoretically, the current setting should be more than sufficient for your needs.
I’ve double-checked the specific behaviors of QuTS hero (ZFS) regarding your 207TB setup.
Please do not go as low as 5% (10TB). For a video editing workflow involving large sequential files, we recommend treating 10% (approx. 21TB) as your minimum free space reservation.
Fragmentation: When a ZFS pool exceeds 90% capacity, the remaining free space becomes fragmented (scattered in tiny blocks across your 12 drives). Above 90% usage, the ZFS algorithms have to work much harder (CPU intensive) to find free blocks, further slowing down your writes.
The “Seek” Problem: To write a new 100GB video file into that 10TB of “swiss cheese” holes, your drive heads have to physically jump around (seek) thousands of times.
Video Editing Impact: Unlike a database, video editing requires high sequential throughput. High fragmentation kills sequential speed, causing dropped frames and timeline stutter, even if you technically have “space” left.
As long as you have enough continuous free space, the ZFS allocator can write files sequentially without needing to defragment. There’s no such utility in ZFS and no need due to the copy-on-write file system and its automatic allocation behaviour.