Question about disk performance

[MSUKvm]

Hello,

I am running ESXi 6.7 U1 (Dell ISO 4 Dec 2018) and have a VM (Windows Server 2016) that has 2 disks, one is an SSD drive (Samsung Evo 860)  and the other is an HDD (Western Digital).

As a test, I copied a 5 GB ISO from the SSD drive to HDD and was getting around 350 MB/s transfer rate, but when I copy from the HDD to the SSD I am getting only 60 MB/s max.  Is this correct as I thought SSD would be a lot faster?

ESXi is currently using the vmw_ahci driver and I have tried to disable this so that it would use the legacy driver, but the transfer speeds are really bad.

Thanks in advance

JD

[a_p_]

What type/model of hardware do you use?

How are the SSD, and HDD connected? Directly to an onboard controller, or to a RAID controller with BBU (write-back cache)?

It's usually a matter of write-back cache which makes the difference, because ESXi itself doesn't do write-caching, and relies on the disk controller's capabilities.

André

[MSUKvm]

Hello,

What type/model of hardware do you use? Dell T130 Poweredge with Samsung 860Evo (SSD) and Western Digital HDD

How are the SSD, and HDD connected? Directly to an onboard controller - Yes with write-back cache enabled in Windows 2016

Thanks