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ISSUE: VSS_E_FLUSH_WRITES_TIMEOUT (MS Exchange server backup)

Article ID: 5348
Reviewed: 18/06/2020

Product Version:
AhsayOBM : or above
OS: Windows

Problem Description

When performing a MS Exchange server backup, the following error message is received in the backup report:

No. Type Timestamp Log
* info ... ...
* erro YYYY/MM/DD hh:mm:ss [VSSDatabaseExpt] VSS_E_FLUSH_WRITES_TIMEOUT
* ... ... ...


The message is returned by the MS Exchange VSS writer.

It indicates the MS Exchange VSS writer was unable to successfully create a VSS snapshot of the MS Exchange database(s) within the default time period due to high disk activity on the server.


To resolve the issue:

  • Check if there is other I/O intensive application(s) that is running on the client computer at the time of the backup.

  • Try adjusting the backup schedule to another time when disk usage is low.

  • Check on the VSS writers:

    • Open an Administrative command prompt and enter the following command:

      vssadmin list writers
      This should output a list of writers and their status, they should all be reported as stable.

      If there is writer listed at unstable, re-register the Volume Shadow Copy Service by following the instructions below:

      • In an administrative command prompt, browse to ${OBM-Install-Home}\bin
      • Execute the 'RegisterVSS.bat' batch file.
      • Reboot the machine.
    Ensure that left-over snapshots are cleaned up:

    • Enter the following command in an elevated command prompt:

      vssadmin delete shadows /all
      This will clean up all VSS snapshots.

      Defect operating system may often accumulate hundreds of VSS snapshots that persist in the system and cause Windows to become un-responsive.
    In some case, you may not be able to delete the VSS snapshots with the above command. Perform the following instead:

    • To decrease the maximum shadow storage size, enter the following command in an elevated command prompt:

      vssadmin resize ShadowStorage /For=C: /On=C: /MaxSize=300MB
      If there is no VSS writer error displayed, but the system is not creating a new VSS snapshot, increase the max shadow storage size on the system instead.

    • To increase the maximum shadow storage, enter the following command in an elevated command prompt:

      vssadmin resize ShadowStorage /For=C: /On=C: /MaxSize=10GB


    obm, exch, exchange, vss, timeout, flush, VSS_E_FLUSH_WRITES_TIMEOUT

    public/5348_vss_e_flush_writes_timeout_during_exchange_server_backup.txt · Last modified: 2020/06/22 09:55 by yuk.cheng