In VMware Virtual SAN 6.2, we introduced several features highly requested by customers, such as deduplication and compression. An overview of this feature can be found in the blog: Virtual SAN 6.2 – Deduplication And Compression Deep Dive.
The deduplication feature adds the most benefit to an all-flash Virtual SAN environment because, while SSDs are more expensive than spinning disks, the cost is amortized because more workloads can fit on the smaller SSDs. Therefore, our performance testing is performed on an all-flash Virtual SAN cluster with deduplication enabled.
When testing the performance of the deduplication feature for Virtual SAN, we observed the following:
- Unexpected deduplication ratio
- High device read latency in the capacity tier, even though the SSD is perfectly fine
In this blog, we discuss the reason behind these two issues and share our testing experience.