Qustion: Will ZFS metadata improve speed up VM storage over NFS and ISCSI

[BrodieCyber]

Hello

I'm relatively new to Truenas. I'm coming from the unRAID world. I haven't used what was then Freenas i years but i needed faster storage for my vms and i want to test out dis-aggregated storage concepts.

My hypervisor of choice is XCP-ng and backend Storage will handled by TrueNAS-SCALE-22.12.0,
My question is simple but will most likely be a long answer. Will ZFS metadata devices running off 2 nvme drives improve the responsiveness of virtual machines running off a HDD based pool that is 2 vdevs of mismatched capacity. I already have 32GB of Ram in the system and am upgrading to 10GBE but is a zfs metadata worth while for VM storage. I know it will benifit the file shares for Windows but would like to know if there is performance to be gained for NFS and ISCSI.

Thanks

 

[jgreco]

backend Storage will handled by TrueNAS-SCALE-22.12.0,

Bad choice. SCALE is not particularly good at iSCSI, or NFS for block storage for that matter.

My question is simple but will most likely be a long answer.

The answer to your question can be summarized as "No".

32GB of Ram

That would come out to 16GB of ARC. We don't recommend trying VM block storage on less than 64GB ARC. Please see

Resource - The path to success for block storage

ZFS does two different things very well. One is storage of large sequentially-written files, such as archives, logs, or data files, where the file does not have the middle bits modified after creation. This is optimal for RAIDZ. It's what most...

www.truenas.com

and also

Resource - Why iSCSI often requires more resources for the same result

iSCSI is a SAN protocol. NFS, CIFS, etc., are NAS protocols. For a NAS protocol, the client sends a command to the filer, such as "open this file", or "read ten blocks", or "remove this file." On the filer, the local NAS protocol daemon...

www.ixsystems.com

It isn't clear why you think "metadata" would somehow benefit. Please see the resource right above to explain why that is not the case.

 

[BrodieCyber]

@jgreco
Hello Thanks for the response and the information.

1) Did not know Scale was not a good choice for block or file level vm storage. I manly chose scale for 2 reasons its Linux based and docker to run containers directly on the NAS for applications that belong on a nas like Minio, syncthing and few more from truecharts.

2) "No" ok understood Thanks

3) I will be reading about the 16GB of ARC that you posted as i like learning and it will be helpful in the future.

4) Was just curious if metadata would make a difference for VM storage as I just didn't know.


Thanks for the help

 

[sretalla]

4) Was just curious if metadata would make a difference for VM storage as I just didn't know.

If the question was "Would a Special/Metadata VDEV help for block storage?", then you may have a better answer... which is... possibly (depending on what your hardware is and how it's configured)