ZFS ZFS on USB 3 attached storage with SSD backed L2ARC?

[ekingston]

Hi all,

I've got a home server built on an Intel NUC. Internally it has a HDD (laptop HDD) and an SSD (one of those M.2 type SSDs). Because of the limited availability for internal storage, I added a couple of USB 3 attached HDDs and set them up as a ZFS mirrored pair. This all works fine as far as it goes.

The USB attached drives are primarily for media storage and the throughput is sufficient so far.

What I'm wondering is, would it be worthwhile to add an L2ARC (or possibly ZIL) on the SSD for the USB attached zpool?

 

[SirDice]

Note that managing L2ARC requires more memory. So you may get better performance just adding more internal memory (which can be used for ARC).

You also need to look at the files themselves, it's not going to cache very large files (typically mediafiles are relatively large) so your L2ARC is most likely just going to sit there doing nothing except use up memory.

 

[ekingston]

Note that managing L2ARC requires more memory. So you may get better performance just adding more internal memory (which can be used for ARC).

You also need to look at the files themselves, it's not going to cache very large files (typically mediafiles are relatively large) so your L2ARC is most likely just going to sit there doing nothing except use up memory.

Thanks for the clarification. That is why I asked. I wasn't sure if there would be much (if any benefit).

The system has 16GB of RAM, which is serious overkill for what is running on the system. Last time I checked, it hadn't even touched swap (although it's got 32GB of SWAP on the SSD just in case).

I will leave it as-is for now.