Adding SSD to my pool?

The Setup:
I8700, 32GB DDR4 @ 3200Mhz, 4X8TB HDD+256GB SSD. 1Gb LAN connection.
TrueNAS SCALE Dragnofish 24.04

The Usage:
File server & Plex server.

The Issue:
I’de like to use the SSD, I know how to add VDAV to the pool but there are several options which fits, Log, Cache and Metadata. I’m not sure which one to use for the best performance. The files I care about are about 1-2GB in size.

Your advices will be very welcome.

You don’t have enough RAM to make effective use of L2ARC (“cache”), and you have no need of a SLOG (“log”). By process of elimination, that leaves only metadata, but keep in mind that if you add that, that device becomes critical to your pool–if it dies, your whole pool goes with it. You might be better off setting it up as its own pool and putting your apps there.


“I have $PIECE_OF_HARDWARE in my drawer and I want to use it” is not a rational process for pool design…

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I’d suggest acquiring a second SSD and using it as a mirrored metadata vdev.

This would accelerate small files. Cache, metadata, Plex stuffs etc

Would need to rebalance the pool (there’s scripts)


A single disk isn’t ideal for anything but a boot drive.

Why you’re so angry?

It is the pain of a man who either learned the hard way several times or has seen too many people ignore good advice.

I used to wonder the same of everyone who had >1k posts on the old forums. But, when I started following their advice life became much easier. Ignore the salt, they mean it in (I assume) good faith.


Beside being a boot drive, a single SSD may be acceptable as an app pool which stores no user data and is backed up to the (much larger) HDD pool or could be rebuilt from scratch in case of drive failure.

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What makes you think there’s any anger there? The post you’re replying to is completely correct–“I have a piece of hardware I want to throw into my system” isn’t a rational way to design a system.