vSphere 6.5 & storage performance issues – vmw_ahci

 In VMware

I am working on my brand-new lab in OVH.net and I have encountered strange storage problems related to my SSDs. I have observer high latencies as well as slow write rates to the storage.

First I thought that I am running unsupported HW and that is the issue but after googling a bit I have discovered that I am not the only one with such problems.

It seems that in VMware vSphere 6.5 there is brand new AHCI driver bundled with installation but now it is quite faulty. Great news is that you can easily switch to old legacy AHCI driver and all your problems will go away.

First check that you might actually be affected by this issue. Navigate to Storage -> Adapter and check what driver is loaded.

As you can see vmw_ahci is loaded

Fall back to old ahci driver

Connect to the ESXi server via SSH

esxcli system module set --enabled=false --module=vmw_ahci

Reboot host

Now you can check again what driver is loaded and at this time it should be good old ahci driver

I hope that this post will help you with playing with VMware vSphere 6.5!

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