VMware VSAN 6.2 Performance & Storage savings



Provisioning Performance




Dedupe & Compression Savings










  1. If I use a M2 PCIe NVMe SSD drive for the cache tier and a single SATA SSD for the capacity tier, can I get 300-400MB/s speeds with this type of setup?

    Also, doesn’t the checksumming slow things down?

    • Yes easily is the simple answer.

      NVMe’s are supported with VSAN so no issue using that for caching tier. The level of performance will depend primarily on your workload profile (Read / Write split, random Vs Sequential & the block size factor…etc.) as well as the capabilities of the NVMe drive used. So from a throughput perspective, yes NVMe will likely perform better than normal SSD’s in the caching tier which already can do significant amount of IOPS, and this IOPS factor is primarily dictated by the NVMe / SSD drive class. So for example, if you assume a basic class D SSD drive (non NVMe) that can do 30K IOPS, assuming a 16K block size (driven by your underlying guest level workload), that’s a total of 30,000*16,384 bytes = 468.75MB/s which will easily be bettered by most if not all NVMe’s which are generally better than SSDs. Most VSAN deployments I see typically use class E SSD’s from server vendors for caching tier which can do up to 60,000 IOPS which means most NVMe’s (that would have similar or higher IOPS characteristics) will also perform better than your stated 400MB/s.

      However note that you are using the Mbps figure here which is better suited for bandwidth rather than throughput. So if you consider the bandwidth also, 400MB/s is easily doable. In an all flash VSAN, only write IO’s are cached and read IO’s are directly served from capacity tier. And the maximum write buffer size (current version of VSAN) is 600GB which means as long as your NVMe drive is bigger than 400MB you are fine, even from a bandwidth perspective.

      Hope this make sense

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