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Can a IaaS with "premium disks" migrate between different availability zones within the same region? RRS feed

  • Question

  • Can a IaaS with "premium disks" migrate between different availability zones within the same region?

    If we wanted to have HA between servers would it be best to use scale sets or a LB between avail zones(AZ) within the same region?   Is there a minimum # of IaaS for a scale set?,... can we do this with two IaaS in a scale set?

    I am thinking a LB cannot migrate between AZs within the same region hence would not provide HA?,... please confirm.


    dsk

    Wednesday, October 2, 2019 2:27 PM

All replies

  • Hi Kimdav,

    Lets go through your question one by one.

    Q: Can a IaaS with "premium disks" migrate between different availability zones within the same region?

    Disks created in a Zone can be attached only to the vms in that zone only. You can move  the disk by creating a snapshot and then creating the new disk from the snapshot.

    Q: If we wanted to have HA between servers would it be best to use scale sets or a LB between avail zones(AZ) within the same region? 

    You need to use both. Load balancers to direct the traffic to direct the traffic to the vms from the VMSS.

    Q: Is there a minimum # of IaaS for a scale set?,... can we do this with two IaaS in a scale set?

    You can do with 1 VM or an availability set or a VMSS.  If thats a single vm, You can directly assign a public ip to it. Attaching an availability set or VMSS makes sense.

    Q: I am thinking a LB cannot migrate between AZs within the same region hence would not provide HA?,... please confirm.

    LB is region wise resource. A single LB can direct traffic to VMS places in all the AZ from a region.

    If you are planning to place a VMSS in in a region with AZ, Then Azure platform takes care of spreading the VMS across zones. It will place the VM's across fault domain in a single AZ as well.

    This blog has more info about the VMSS in availablity zones.

    Thursday, October 3, 2019 8:58 AM
    Owner
  • Hello,

    Any update on the issue?

    If the suggested answer helped you solve your query, do click on "Mark as Answer" and "Up-Vote" on the answer that helped you for the benefit of other community members.

    Thanks.
    Monday, October 7, 2019 11:49 AM
  • Hi Kimdav,

    Did the above reply helped you to solve your problem?

    For the benefit of the community, Please click on "mark as answer" for the reply which helped you to solve your problem.

    Thursday, October 17, 2019 12:44 PM
    Owner
  • Another question(s).

    When we have a scale set this requires a LB?  Can I assume this is a azure LB?,... as opposed to a F5.  If we place VMs into a scale set can we assume that availability sets do not need to be configured?,... because normally VMs in a availability set involve a LB (VMs located in the same datacenter).  VMs behind a LB in availability zones ( not in same datacenter ) do not need an availability set configured? I thought all HA involving a LB required the VMs to  be in a availability set?

    My understanding that all VMs associated with a LB (not including a scale set) require an availability set yet you are telling me a LB can have VMs in different zones?   An availability set is not in different zone but in the same datacenter?  Availability zones do not require availability set to be added to the LB?,... I though all VMs had to be in an availability set to be added to a LB???

    Are VMs added to a LB individually and are not added as an availability set (ie three VMs together at once)?  Hence a LB is not aware during the configuration whether a VMs are in a availability set?  We can VMs to a LB whether they are in a availability set or in a availability zone?

    Is there any cost advantage to have a scale set versus a regular LB / availability zone?  Is there any advantage of the LB over the scale set other than the automatic scaling of VMs?   If we have both VMs whether in a scale set in the same availability zone as the DB server would we not get better performance?   Does this performance increase apply to VMs in an availability set within the same availability zone?   



    dsk






    • Edited by kimdav111 Tuesday, October 22, 2019 6:35 PM
    Tuesday, October 22, 2019 5:42 PM
  • Hi,

    Find my answers inline.

    Question: When we have a scale set this requires a LB?  Can I assume this is a azure LB?,... as opposed to a F5.  If we place VMs into a scale set can we assume that availability sets do not need to be configured?,... because normally VMs in a availability set involve a LB (VMs located in the same datacenter).  VMs behind a LB in availability zones ( not in same datacenter ) do not need an availability set configured? I thought all HA involving a LB required the VMs to  be in a availability set?

    Yes. Thats a Azure Load balancer.

    If you place vms in a sclae set, You dont need to have a availability set. By default vms will be places across  fault domains. VMSS use placement groups. Reference: https://docs.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-placement-groups

    Q: My understanding that all VMs associated with a LB (not including a scale set) require an availability set yet you are telling me a LB can have VMs in different zones? 

    LB can have vms from multiple zones if you point that to a VMSS with multiple zones.  Else availality set is needed

     Q: An availability set is not in different zone but in the same datacenter? 

    Yes. Availability sets works at the data center level.

    Q: Availability zones do not require availability set to be added to the LB?,.

    You cant specify zones if you are using availability sets.  Thats why you need to use VMSS with zones.


    Q. I though all VMs had to be in an availability set to be added to a LB???

    You cant specify a zone if you specify a availability set.  You can add only one vm to the LB if its not part of any availability zone(not recommended). If you are region is having zones and you want to utilize it, USe VMSS with zones.

    If you dont want to use or consider zones go with availability sets

    Q

    Is there any cost advantage to have a scale set versus a regular LB / availability zone?  Is there any advantage of the LB over the scale set other than the automatic scaling of VMs?   If we have both VMs whether in a scale set in the same availability zone as the DB server would we not get better performance?   Does this performance increase apply to VMs in an availability set within the same availability zone?

    No cost advantage. You will be charged for the load balancer and the number of vms used.

    VMS in the same availablity zones will have good performance.  You can think if cross zone communication as co located datacenters.

    Wednesday, October 23, 2019 10:32 AM
    Owner