Iscsi datastore dqlen change

[ManivelR]

Hi,

First of all, this is pre prod environment.

I have connected my esxi 6.7 cluster Esxi hosts with s2d cluster.

S2d cluster has two windows 2019 servers. Each server has local nvme, ssd and HDD disks. We configured with these three type of mentioned disks with s2d cluster.

Provisioned the s2d storage to esxi cluster via iscsi.

I have a latency issues on esxi vms.

From esxi,it uses software iscsi adapter.

I have disabled delayed acknowledgement.

I have changed the iscsi max io size to 512 in command line.

I have changed the iscsi datastore disk queue depth to 64 from 128 via command line(dqlen) . However, it automatically changes while do file copy from windows 2019.I don't know why?

But still, I'm seeing the less throughout (when I copy any files between drives in windows 2019).In ESXTOP-V-- I'm seeing wr/latency as 80 ms.

Any idea?  Any other setting is needed in esxi to get good throughout?

Please note, this is not a production setup and like to get advice from you.

This is not a compatible setup. I'm aware.

Thank you

[BerndtSchumann]

Have a chance to double-check the performance one you have tweaked MTU settings. Setting Jumbo Frames to 9k might help. These pages are related to the setting.

VMware Knowledge Base

https://www.360ict.nl/blog/jumbo-frames-s2d/

[ManivelR]

Thanks much for the response. It makes sense..We are also in the same situation.

We are using three tiers (nvme+ssd+hdd)for s2d windows 2019,however it is providing below the 10 k iops only.

We have not tested with mtu change yet and like to test this.

As per the article, 4096 mtu will make much difference compare to mtu 9000.

Is that right? And I need to change the mtu value from switch interfaces side, s2d side and esxi end.

Thank you,

Manivel R