Adding L2ARC using Virtual Disks

[xpr3ss]

Hello,

I'm a beginner to FreeNAS so trying to learn as much as I can. I've been following the build guide from: https://www.ixsystems.com/community...0sdv-tln4f-esxi-freenas-aio.57116/post-402506, however I'm using FreeNAS 11.3-U4. How would I go about adding L2ARC as described in the build guide using the UI in 11.3? It says to go to Storage -> Volumes, Volume Manager and to extend the Volume however it's not clear how I would replicate that in the latest FreeNAS UI.


Thank you in advance.

 

[Spearfoot]

Hello,

I'm a beginner to FreeNAS so trying to learn as much as I can. I've been following the build guide from: https://www.ixsystems.com/community...0sdv-tln4f-esxi-freenas-aio.57116/post-402506, however I'm using FreeNAS 11.3-U4. How would I go about adding L2ARC as described in the build guide using the UI in 11.3? It says to go to Storage -> Volumes, Volume Manager and to extend the Volume however it's not clear how I would replicate that in the latest FreeNAS UI.


Thank you in advance.

That guide is for configuring FreeNAS as a virtual machine on the VMware ESXi hypervisor. Is that what you are doing?

If not -- if you're running FreeNAS on a system, not as a virtual machine -- then to add an L2ARC device you will need to install a disk (SSD, M.2 SSD, etc.) on the system and add it to your pool.

But read the ZFS primer first to see if you will even gain any benefit from an L2ARC device:

27. ZFS Primer — FreeNAS®11.3-U4 User Guide Table of Contents

www.ixsystems.com

 

[xpr3ss]

That guide is for configuring FreeNAS as a virtual machine on the VMware ESXi hypervisor. Is that what you are doing?

If not -- if you're running FreeNAS on a system, not as a virtual machine -- then to add an L2ARC device you will need to install a disk (SSD, M.2 SSD, etc.) on the system and add it to your pool.

But read the ZFS primer first to see if you will even gain any benefit from an L2ARC device:

27. ZFS Primer — FreeNAS®11.3-U4 User Guide Table of Contents

www.ixsystems.com

Thanks for the link, i'll read through. Yes I'm installing FreeNAS on ESXi. I've created the virtual hard drive on the SSD attached to the FreeNAS host, but was lost how to accomplish adding it. Thanks again!

 

[Patrick M. Hausen]

You mean you created a vmdk on the drive served by FreeNAS via iSCSI or NFS to ESXi and you want to add that as an L2ARC? You are aware that this will destroy your performance more than anything else?

 

[xpr3ss]

Sorry, I didn't realize that was the consequence. I was mainly following the guide that said: https://www.ixsystems.com/community...0sdv-tln4f-esxi-freenas-aio.57116/post-402506

There is a fast M.2 NVMe disk with 250GB available installed in this system, but the ESXi install and the FreeNAS boot disk only use about 12GB of that. Seems like a waste.

Although, best recommendations are to provide FreeNAS with physical access to disks, the swap and l2arc devices are ephemeral, and thus it doesn't really matter if they are virtual devices.

In my testing, the VMware pass-through virtual devices are quite performant.

So, I'll create a couple of Virtual disks in the FreeNAS VM, and use those for swap and L2ARC.


I have the identical setup and am trying to follow the similar process, but it sounds like it's not a good idea. Thanks for the heads up, I'll leave up the l2arc.

 

[Patrick M. Hausen]

If the disk is assigned to ESXi and formatted with VMFS and you use it for the VMware and FreeNAS boot media, then you can also add a VMDK for an L2ARC if that makes sense for your workload.
I read your description as:

• the physical disk is passed-through to FreeNAS
• it's formatted as a FreeNAS pool with ZFS
• you export it back to ESXi via either iSCSI or NFS
• you create a VMDK on that
• you assign that VMDK back to the FreeNAS VM and intend to use it as L2ARC

I would definitely not do that. The former - as always: it depends.

HTH,
Patrick