Exam 3V0-21.21 topic 1 question 59 discussion

The customer wants "high availability requirements for the legacy applications virtual machines". B. Enable Fault Tolerance Will provide the best option here for HA. A. Enable vSphere HA and add a VM Override with VM Restart Priority set to Disabled No - By default all VMs will have the “medium” restart priority. Disabling it won't provide any HA C. Achieve application availability with snapshots Not a great solution at all. D. Enable vSphere HA and add a VM Override with VM Restart Priority set to Lowest No - By default all VMs will have the “medium” restart priority. Setting it to Lowest will DECREASE HA vSphere HA Restart Priority https://www.yellow-bricks.com/2018/04/04/vsphere-ha-restart-priority/

Right answer is B. We want a 99,99% SLA on the legacy applications : that represents only (more or less) 4 minutes of unavailability per month, which is very short. A&D : vSphere HA could be solution (hoping the VMs will start fast enough), but setting a priori to Disabled or Lowest is a non-sense. C : Snapshots do not achieve anything in terms of availability. It only helps with recoverability. B : Fault Tolerance is the only option here, even if there are a lot of constraints to implement it.

FT with all the assumptions that brings in the conversation will provide the desired SLA by having replica machines. One hour downtime a year per VM narrows down the option to FT. Other options does not offer any SLA measure. HA can experience issues if there is capacity constrain and bottleneck of power on tasks. Snapshots relay on intervention and there time is wasted. What if snapshot can't be used? SLA level of 99.99 % uptime/availability results in the following periods of allowed downtime/unavailability: Daily: 8.6s Weekly: 1m 0.48s Monthly: 4m 21s Quarterly: 13m 2.4s Yearly: 52m 9.8s

FT isn’t simple

B is correct

B is correct, see nemisis95. this is only to get the votes in the correct place

Should we keep in mind: The maximum number of fault-tolerant VMs allowed on a host in the cluster is 4. Both Primary VMs and Secondary VMs count toward this limit.

Really a bad written. it must be D. B: FT has limitation of CPU, vSphere Liz. etc

From my point of view, ans D should be "Highest" priority instead of "Lowest", maybe is a typo. FT has too many requirements... not a good idea for legacy apps.. As it is right now, I go for B, but if we change this word in option D, I will prefer it

Really a bad question.. If it is "The customer states that there is no application level availability for legacy applications." which means legacy apps is not available then the answer is D If it is ""The customer states that there is no application level HIGH availability for legacy applications." then the answer should be B

I believe B , First , legacy application need 99.99% SO, HA is base and HT is best ! D , If you enable HA , why not keep default or set Highest but degree the priority ?

I believe is D "The customer states that there is no application level availability for legacy applications." no application level availability, so it does not matter if the priority is the lowest. Therefore, "Enable vSphere HA and add a VM Override with VM Restart Priority set to Lowest" - D

My guess is to probably keep it simple and choose D - Enable vSphere HA and add a VM Override with VM Restart Priority set to Lowest

Bad question really. Can VM Restart Priority set to Lowest let us achieve 99.99 % SLA Daily: 8s Weekly: 1m 0s Monthly: 4m 22s Quarterly: 13m 8s Yearly: 52m 35s Take a guess - B for FT, or D for HA

I've gone back to my original answer - B Answer is Fault Tolerance. The customer wants "high availability requirements for the legacy applications virtual machines"/ D is setting the Legacy Application VMs to have a VM Restart Priority set to Lowest. A is disabling it altogether. By default all VMs will have the “medium” restart priority on a cluster HA settings. https://www.yellow-bricks.com/2018/04/04/vsphere-ha-restart-priority/ C wouldn't meet a HA requirement so it leaves FT as the solution.

Changing to D as Fault Tolerance has too many Requirements and Limits

d: https://docs.vmware.com/en/VMware-vSphere/6.0/com.vmware.vsphere.avail.doc/GUID-3DAED2B1-55B8-4877-BD0F-BC57C10A516C.html#:~:text=The%20restart%20priority%20determines%20the,on%20a%20per%2Dhost%20basis.