What should be done to avoid these issues?

A storage administrator discovers vSAN is rebalancing components across a cluster randomly and faces degraded performance on the applications. What should be done to avoid these issues?
A. Size at least two disk groups on each node
B. Maintain a minimum of 10 percent unused capacity
C. Keep total storage consumption <70 percent
D. Ensure there is sufficient queue depth on the I/O Controller

microsoft-exams

7 thoughts on “What should be done to avoid these issues?

  1. I’d say C. Whist queue depth is important, the question goes out of it’s way to specify that rebalancing is happening randomly which is more a symptom of too much consumption.

  2. Right answer is D

    Queue depth is extremely important, as issues have been observed with controllers that have very small queue depths. In particular, controllers with small queue depths (less than 256) can impact virtual machine I/O performance when vSAN is rebuilding components, either due to a failure or when requested to do so when entering maintenance mode.

    https://storagehub.vmware.com/t/vmware-r-vsan-tm-design-and-sizing-guide-2/choosing-a-storage-i-o-controller-1/

  3. C is the correct answer!

    According to VMware documentation, “Keep at least 30 percent unused space to prevent vSAN from rebalancing the storage load. vSAN rebalances the components across the cluster whenever the consumption on a single capacity device reaches 80 percent or more. The rebalance operation might impact the performance of applications. To avoid these issues, keep storage consumption to less than 70 percent. ”

    https://docs.vmware.com/en/VMware-vSphere/6.7/com.vmware.vsphere.vsan-planning.doc/GUID-581D2D5C-A88F-4318-A8B3-5A5F343F1247.html

  4. Support for D

    “A good practice is, from time to time, to re-check that everything is behaving
    correctly from an ESXi perspective. One of the most critical items related to storage
    is the queue depth, and we have seen the negative impact that small queue depths
    can have on Virtual SAN performance.:

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