Conversions filling system disk: Any way to set a storage cap?

[me@jackbenda.com 6]

I've been experimenting with Emby's built-in conversion feature and ran into a problem I suspect others have hit too: conversions writing to the system disk until it's completely full.

The Conversions settings page only gives me two controls: A temporary file path and the full speed toggle. There's no native option to limit how much disk space conversions are allowed to use, or to cap the queue size.

My setup: Emby running natively on Ubuntu Server 24.04, 231GB NVMe system disk. When I kicked off a batch of conversions, Emby happily wrote to /var/lib/emby/sync/ until the drive was full. No warnings, no throttling, just a dead server.

A few questions for the community:

1. Is there a setting I've missed that limits conversion disk usage? I've only found the temporary file path and the speed toggle.
2. Is there a way to limit how many conversions run concurrently, to at least control the rate at which disk is consumed?
3. For those running conversions on a system disk — what's your approach? Redirect to a separate drive, or something else?

If this genuinely isn't possible natively, I'll put in a feature request: A maximum disk usage cap for conversions seems like a fairly essential guardrail. Keen to hear how others are handling this before I go the OS-level workaround route (create a dedicated directory on the NVMe for conversions, then enforce a hard size limit using a fixed-size loopback mount. Emby hits the ceiling and stops. system disk is safe. I'd point the "Temporary file path" at that mount. The cap is whatever I set, say 50GB, and nothing else on the disk is at risk. I'm just worried that that could freeze Emby up entirely though.)