Why only 538Gb Usable on 2.7Tb Pool?

Hello everyone,

I’m currently experimenting with TrueNAS, and I’ve noticed that when I create a SingleDrive pool (because it’s a hardware RAID), the pool size is displayed as 2.73TB, but in the dataset, it shows as 538.75GB usable. I’ve replicated this behavior on a second productive system. What could be causing this, and how can I change it?

Thank you in advance and best regards

Don’t. Just don’t.

Truenas uses software raid, it does not play well with hardware raid. Let truenas handle the raid configuration.

As for your original question: you didn’t give any useful information to answer that. We don’t know the size of the drives nor the raid layout. Don’t bother with it though, get rid of the hardware controller or whatever you are using and setup a RAIDZ configuring truenas.


Flash your HBA or raid controller into IT mode, and PCIE passthrough if you are virtualized or just passthrough fully to TrueNas as IT HBA, and let TrueNas handle everything; otherwise you are asking ALOT of trouble. This is bit old but still relevent:

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:point_up: :point_up: :point_up:

It’s post like these that I wish Discourse had a “triple” pointing up reaction.

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@Simone-Alicia, in good conscience, no one can really help you resolve this issue until you redo your setup without the use of “hardware RAID”. There is no “making it work” with your current setup. It’s a sure path to data loss. Period.