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Dynamic Disk

    Question

  • Has Microsoft published any recent best practices around using Dynamic Disks in Windows 2016 DC Edition w/Hyper-V cluster?

    I've ready tons of conflicting articles about using them in just LAB,DEV,TEST, but never Prod. Some say Prod is ok after 2012. I found one that says don't use Dynamic Disk in a cluster. Some say always use Dynamic unless the vendor recommends fixed. On and on and on...

    I just can't find an "official" article from Microsoft that I can use to present to some colleagues.

    Any help would be greatly appreciated.

    Thanks

    Thursday, August 9, 2018 5:32 PM

Answers

  • Hi,

    Fixed disks use the total amount of space on the host immediately, while dynamic disks grow as you fill them with data.

    It is said that fixed disks are a bit faster, but with the hardware we have as of this day you will never notice any difference, I personally never seen any difference. Creating a fixed disk for performance reasons is not worth it.

    From personal experience I've been using dynamic disks in production for years and have not had any issues.

    I believe all these talks about using Fixed disks are dated back to when they came out with Server 2008.


    Best regards,
    Leon


    Blog: https://thesystemcenterblog.com LinkedIn:

    • Marked as answer by Heybuzzz76 Monday, August 13, 2018 2:33 PM
    Thursday, August 9, 2018 7:40 PM
  • Hi ,

    When using the VHDX format, it is recommend that you use the dynamic type because it offers resiliency guarantees in addition to space savings that are associated with allocating space only when there is a need to do so. 

    As a dynamically expanding disk, it will continue to grow up to -- but not more than -- the size specified. 

    Though, as it is possible to create a dynamic disk that is larger than the size of your physical hard drive. If this happens, it can affect all the VMs on that volume. 

    I would suggest you monitor your disk space closely and be sure not to overcommit when you use dynamical disk.

    Best Regards,

    Candy


    Please remember to mark the replies as an answers if they help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com   

    • Marked as answer by Heybuzzz76 Monday, August 13, 2018 2:33 PM
    Friday, August 10, 2018 3:10 AM

All replies

  • Hi,

    Fixed disks use the total amount of space on the host immediately, while dynamic disks grow as you fill them with data.

    It is said that fixed disks are a bit faster, but with the hardware we have as of this day you will never notice any difference, I personally never seen any difference. Creating a fixed disk for performance reasons is not worth it.

    From personal experience I've been using dynamic disks in production for years and have not had any issues.

    I believe all these talks about using Fixed disks are dated back to when they came out with Server 2008.


    Best regards,
    Leon


    Blog: https://thesystemcenterblog.com LinkedIn:

    • Marked as answer by Heybuzzz76 Monday, August 13, 2018 2:33 PM
    Thursday, August 9, 2018 7:40 PM
  • Hi ,

    When using the VHDX format, it is recommend that you use the dynamic type because it offers resiliency guarantees in addition to space savings that are associated with allocating space only when there is a need to do so. 

    As a dynamically expanding disk, it will continue to grow up to -- but not more than -- the size specified. 

    Though, as it is possible to create a dynamic disk that is larger than the size of your physical hard drive. If this happens, it can affect all the VMs on that volume. 

    I would suggest you monitor your disk space closely and be sure not to overcommit when you use dynamical disk.

    Best Regards,

    Candy


    Please remember to mark the replies as an answers if they help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com   

    • Marked as answer by Heybuzzz76 Monday, August 13, 2018 2:33 PM
    Friday, August 10, 2018 3:10 AM
  • Candy / Leon - 

    Thanks for the info and real world examples. I spoke to my storage vendor and they also said Dynamic would be fine w/o noticing any performance hit.

    Thanks

    Monday, August 13, 2018 2:35 PM
  • Hello,

    I have recently checked the performance for both Dynamic and Fixed disks and can tell that read operations are good on Dynamic disks while random write operations are extremely poor, which is expected due to its nature.

    Fixed disks perform close to underlying storage which was RAID5 on spindles.

    So, if you don't need high performance, you can use dynamic disks in production without any issues.


    • Edited by LaMerk Monday, August 13, 2018 4:37 PM
    Monday, August 13, 2018 4:35 PM