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L2ARC question

Western Digital Drives - The Preferred Drives of FreeNAS and TrueNAS CORE

wdp

Junior Member
Joined
Apr 16, 2021
Messages
19
I'm just tinkering around with my build at the moment, so excuse my ignorance as I can't find much in the documentation about this.

I got a PCIE dual m2 card in today and I wanted to make sure the motherboard/system could see it and detect and M2 since the motherboard doesn't officially support it based on the lack of information in the supermicro manuals. I have 2x Micron 7300 PRO 480GB's in the mail but they haven't arrived yet. So I grabbed a spare 512gb 970 Pro I had in the inventory and hooked it all up.

BOOM, it works! Small victories.

My question is...

Can turn a single m2 into L2ARC, or if that require two m2 in order to even create it? I don't currently even have the option to hit create if I add it to a cache vdev.

 

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jgreco

Resident Grinch
Moderator
Joined
May 29, 2011
Messages
14,161
You can have one or two L2ARC devices. They do not need to be (and should not be) mirrored. It isn't clear if there is value in going beyond two devices. Please make sure you have sufficient memory; a bare minimum of 64GB is really needed so that ZFS has sufficient ARC to identify what to evict to the L2ARC, probably 128GB of RAM is better to support 1TB of L2ARC.
 

wdp

Junior Member
Joined
Apr 16, 2021
Messages
19
Thanks for the info. I have 64RAM for this trial build. This is more just me getting and testing and learning than the actual build / performance / fine tuning.

I ran into an error last night after installing the PCIE card and I can see the NVME in the slot, but don't have the option to add it to a caching vdev. So I plugged in two drives into spare bays and same thing, I don't have the option to add them as a vdev.

Still learning but now to troubleshoot that.
 

wdp

Junior Member
Joined
Apr 16, 2021
Messages
19
I take that back, I can create a vdev with the addition drive bays, but do not have to option to hit create on the nvme drive for a caching vdev.
 

wdp

Junior Member
Joined
Apr 16, 2021
Messages
19
Scrub this, I clearly need to slow down and misconfigured my vdev setup for my pool. All appears to be good now.
 
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