F2-221 Load at 100% (CPU only 23%) running Jellyfin, also asking about 4K HDR/DV transcoding capability

[hangson10374]

Hi everyone,
I'm running a TerraMaster F2-221 with TOS 7.0.0612 and Jellyfin, and films downloaded from qBittorrent. I go outside and watch films through Jellyfin destop app, not web. The network speed is perfect.
At first, it can play films smoothly with 2160p iT WEB-DL DDP5.1 Atmos DV HDR H.265 format. But after that, when I play 2160p UHD BluRay REMUX DV HDR HEVC DTS-HD MA 7.1 format, it has a problem.

• Load: 100% ("System is sluggish")
  CPU: only 23%
  Memory: 66% (1.17GB / 1.78GB)
  HDD Busyness: 4.43%
  Network: almost no traffic (1.25 KB/s up, 424 B/s down)

And I can't access the NAS anymore. When I login TNAS PC it showed Connection time out. And I just have only choice is reset NAS through TNAS mobile.
Can someone tell me what happen please?

[Gremlin]

You might need to increase your memory. I don't use the apps you are using, but I have run 10GB* Ram from the outset and have not seen any similar issues (as far as I can recall).

*On-Board 2GB plus additional 8GB stick.

[MikeZhang]

The "2160p UHD BluRay REMUX DV HDR HEVC DTS-HD MA 7.1" format you mentioned is basically the highest-specification video file available for consumer use, with the following characteristics:

Extremely high bitrate: REMUX Blu-ray discs typically have a bitrate of 50-100 Mbps or even higher, far exceeding the previously smoothly played WEB-DL format (usually 15-25 Mbps).

Complex encoding: HEVC (H.265) decoding itself requires significant computing power.

DTS-HD MA 7.1 audio: Transcoding or passing through lossless audio can also increase the system load.

When your F2-221 attempts to process such "extreme" files, it triggers a series of chain reactions:

Instant resource exhaustion: The F2-221 is an entry-level dual-bay NAS with limited CPU performance. When processing such high-bitrate files, CPU or memory usage can instantly spike to 100%.

System unresponsive: When system resources (especially memory) are exhausted, the TOS operating system will become unresponsive, making it impossible for you to access it in any way.

It's recommended to upgrade to more powerful NAS if you have long term need to play UHD films.

[hangson10374]

The "2160p UHD BluRay REMUX DV HDR HEVC DTS-HD MA 7.1" format you mentioned is basically the highest-specification video file available for consumer use, with the following characteristics:

Extremely high bitrate: REMUX Blu-ray discs typically have a bitrate of 50-100 Mbps or even higher, far exceeding the previously smoothly played WEB-DL format (usually 15-25 Mbps).

Complex encoding: HEVC (H.265) decoding itself requires significant computing power.

DTS-HD MA 7.1 audio: Transcoding or passing through lossless audio can also increase the system load.

When your F2-221 attempts to process such "extreme" files, it triggers a series of chain reactions:

Instant resource exhaustion: The F2-221 is an entry-level dual-bay NAS with limited CPU performance. When processing such high-bitrate files, CPU or memory usage can instantly spike to 100%.

System unresponsive: When system resources (especially memory) are exhausted, the TOS operating system will become unresponsive, making it impossible for you to access it in any way.

It's recommended to upgrade to more powerful NAS if you have long term need to play UHD films.

I've also been considering that, so I'm looking into newer-generation NAS models to upgrade. However, before concluding that the cause is the CPU and that upgrading is the only option, I'd like to clarify: why is the Load at 100% while CPU and Memory usage are both quite low? And would the F2-425 already be sufficient for my needs?

[hangson10374]

The "2160p UHD BluRay REMUX DV HDR HEVC DTS-HD MA 7.1" format you mentioned is basically the highest-specification video file available for consumer use, with the following characteristics:

Extremely high bitrate: REMUX Blu-ray discs typically have a bitrate of 50-100 Mbps or even higher, far exceeding the previously smoothly played WEB-DL format (usually 15-25 Mbps).

Complex encoding: HEVC (H.265) decoding itself requires significant computing power.

DTS-HD MA 7.1 audio: Transcoding or passing through lossless audio can also increase the system load.

When your F2-221 attempts to process such "extreme" files, it triggers a series of chain reactions:

Instant resource exhaustion: The F2-221 is an entry-level dual-bay NAS with limited CPU performance. When processing such high-bitrate files, CPU or memory usage can instantly spike to 100%.

System unresponsive: When system resources (especially memory) are exhausted, the TOS operating system will become unresponsive, making it impossible for you to access it in any way.

It's recommended to upgrade to more powerful NAS if you have long term need to play UHD films.

I've also been considering that, so I'm looking into newer-generation NAS models to upgrade. However, before concluding that the cause is the CPU and that upgrading is the only option, I'd like to clarify: why is the Load at 100% while CPU and Memory usage are both quite low? And would the F2-425 already be sufficient for my needs?

Wait, I just got home, and now watching through the Jellyfin app works fine — the NAS isn't freezing up?? What's going on here?

[MikeZhang]

The True Meaning of 100% Load

In Linux, load refers to the total number of processes that are running or in an uninterruptible sleep (D state) state.
If your TNAS has a 4-core CPU, a load of 4.0 means it's fully loaded (100%).
High load, but idle CPU, indicates that a large number of processes are queuing for "some resource" rather than using the CPU for computation.

Possible reason: Disk I/O wait (most likely cause, probability > 80%)
When a process needs to read or write to the hard drive, but the hard drive is extremely slow or busy, the process enters the "D state" queue. This causes the load to spike, but the CPU and memory remain idle.

For your usage scenario, the F2-425 Plus, equipped with a more powerful CPU, would be a better fit, positioned as an advanced/semi-professional device aimed at users with high-performance needs.

[MikeZhang]

The reason Jellyfin plays normally is that it uses large, sequential read operations when reading media files. The Linux kernel has highly optimized this type of operation (Direct I/O), eliminating the need for frequent disk seeks and allowing direct access to the underlying network. Therefore, even with long queues at the parking lot entrance, Jellyfin can still smoothly enter and exit through its dedicated lane.