vSAN encryption - performance impact

[mithrandir1030]

I found below document which explains a little about performance impact when vSAN encryption is enabled.

The Code Keepers: vSAN Native Encryption - Part 1 - Virtual Blocks

-> There is minimal impact to CPU cycles while we encrypt data. This is fundamental to how encryption has been designed for vSAN. For most workloads (with AES-NI enabled) we expect somewhere between 5-15% CPU penalty and no performance overhead. This overhead is representative of running vSAN with dedupe and compression turned on.

However, I am a little confused  that what does 5-15% CPU penalty mean? Means CPU speed will become slower at 5-15%?

And what does "This overhead is representative of running vSAN with dedupe and compression turned on" mean? When the dedupe and compression is enabled, there is no performance overhead ?

It will be appreciated if anyone could explain more detail.

[Duncan Epping]

it means that your CPU utilization may go up with 5-15%, depending on the IO of course. Which is similar to the increase you would see when you enable Deduplication and Compression.

[mithrandir1030]

Thank you so much. I see. Penalty is about utilization not speed.

And about the second question(performance overhead), could you explain a little more ?