Win 2019 Hyper-V failed to generate delta - Error: Size of change tracking file exceeded the maximum size limit. (0xC03A0021) RRS feed

  • Question

  • I replicated Windows 2012 R2 VM from Windows 2012 R2 Hyper-V host to Windows 2019 Hyper-V.

    Then removed replication and enabled replication of the same VM to another Windows 2012 R2 host. Initial replication succeed and in general it works fine, but every morning it stops with the following error messages and requires resynchronisation:

    Hyper-V could not perform the change tracking action for virtual machine 'VM Name'. (Virtual machine ID C30836E4-6AA2-4253-BADF-4560AB3EF737)

    Failed to switch the change tracking log file for virtual machine 'VM Name'. (Virtual machine ID C30836E4-6AA2-4253-BADF-4560AB3EF737) - Error: Size of change tracking file exceeded the maximum size limit. (0xC03A0021) 

    Virtual machine 'VM Name' requires resynchronization to get back into an operational state. (Virtual machine ID C30836E4-6AA2-4253-BADF-4560AB3EF737)

    Hyper-V failed to generate delta for virtual machine 'VM Name': Operation aborted (0x80004004). (Virtual machine ID C30836E4-6AA2-4253-BADF-4560AB3EF737)

    I suspect it happens due to full MSSQL server backup taking place inside the VM overnight into one of its disks and that disk is a part of the replication. The size of the backup disk is 1Tb.

    Having said that this has been working fine for a number of years on the original Windows 2012 R2 host and the same VM with all the disks (including 1Tb backup disk) was happily being replicated to another Win 2012 R2 host without any issues. The only change now is that this VM is now on Win 2019, so why would it fail to work on Win 2019?

    Thursday, May 21, 2020 2:10 PM

All replies

  • Hi etegc,

    "Replication might stop working if the Primary Server does not have enough storage available on volume where HRL files are stored. Primary Server tracks changes on the Primary Virtual Machine and creates HRL (Hyper-V Replication Log) files. The HRL files are stored in the directory where virtual machine VHD files reside. These HRL files are replicated to the Replica Server."

    So, please check if the new 2019 "Primary" Server has enough disk space to store the HRL file.

    Below is the article about troubleshooting Hyper V replication, for your reference:

    (Note: this is a third-party article, since it may change its content without notification, we do not guarantee its security.)

    Best Regards,


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    Friday, May 22, 2020 6:39 AM
  • That's not the problem - there is plenty of storage at source and destination.

    Furthermore, after resynchronisation that happens every day after this failure, the replication continues to work until next morning when it fails again with the same issue.

    Friday, May 22, 2020 9:31 AM