Server 2012 Hyper-V Backup fails Volsnap 25


  • I am attempting to use Windows Server Backup in Server 2012 to backup Hyper-V servers and guests and having the volsnap 25 error issue. I have attempted to apply the suggestions in the following 2003 article but need clarification:

    My configuration has two logical volumes:
    C: 1TB (2x 512GB RAID0) SSD (Operating System - full datacentre install, and Virtual Guests)
    F: 4TB (2x 2TB RAID0) HDD (Backup only) 

    I am simply backing up the SSDs to the HDDs, all drives are local. Unfortunately the SSDs seem to be far too fast for the HDD to cope with. The article suggests "Compute a value that is five percent of the smallest shadow copy storage space on any one volume on the system" So for my setup as I am only backing up one physical drive should this be 50GB? Or do I have to take into account the storage space on my virtual guests? 

    I attempted with the maximum 3GB from the guide but this also failed.

    Monday, January 07, 2013 1:54 PM


All replies

  • Hi Andy,

    Please check event logs to see if there is any detailed error message related to this error. Also try to perform a vssadmin list writers and show us the result.

    Meanwhile this should be a similar issue, you could have a look to see if there is anything helpful:

    TechNet Subscriber Support in forum |If you have any feedback on our support, please contact

    Wednesday, January 09, 2013 7:34 AM
  • Hi Andy,

    Can you share event logs for volsnap? Let me have a look,



    Wednesday, January 09, 2013 9:10 AM
  • This is the Volsnap error from last night, the backup starts at 2:30AM and usually takes around 30 minutes, when the issue occurs the backup continues well in to the next working day preventing us from managing the virtual machines. I have just noticed there are some warnings that I'm not sure were there before:

    Log Name:      System
    Source:        volsnap
    Date:          23/01/2013 09:41:01
    Event ID:      25
    Task Category: None
    Level:         Error
    Keywords:      Classic
    User:          N/A
    Computer:      ATS-VS01.XXXXXXX.COM
    The shadow copies of volume F: were deleted because the shadow copy storage could not grow in time.  Consider reducing the IO load on the system or choose a shadow copy storage volume that is not being shadow copied.
    Event Xml:
    <Event xmlns="">
        <Provider Name="volsnap" />
        <EventID Qualifiers="49158">25</EventID>
        <TimeCreated SystemTime="2013-01-23T09:41:01.107687900Z" />
        <Security />

    Wednesday, January 23, 2013 1:24 PM
  • Hello

    i can tell you for sure that these are errors related to your ssd and raid controller, unfortunately it is not easy to handle particular operations like backup with ssd drives especially if they are not enterprise class.. 

    especially the disk I/O errors and  as you see you have an iscsiprt error too.

    i can tell you.. that findindg a solution will be not easy.. 

    the problem is also the cache/speed differencing from the ssd to the hdd, in this case and related shadow copies process to mount and dismount during..

    in 2012 year i tried to implement for the most ssd's for the os partition in servers.. since i am a very ssd big fun,, but.. i can tell you that i always had and still having some problems.. only in high end hardware all combined everything is working without a hitch.

    my only suggestion is check everything on your server is up to date.. drivers and firmwares..

    then i would check for similar posts on the ssd drive forum and raid controller forum related too.


    ------------------------------------------------------- I understand a little computers.

    • Edited by Ales75 Saturday, January 26, 2013 7:50 AM spelling
    Saturday, January 26, 2013 7:48 AM
  • if you have the chance... an interesting try would be installing a further ssd and try to perform backup from on the ssd, i bet wont be a full fix, but of course the errors situation will change.

    then check your vss writers..if they are good 

    vssadmin list writers

    then another it could be to increase the the space on the diff area used by vss.. by default should be 300


    reg word in mb. increase it much more.. to try if it makes difference.. for example 2000.

    you can understand that shadows storage is on disks much slower the ssd

    ------------------------------------------------------- I understand a little computers.

    • Edited by Ales75 Saturday, January 26, 2013 8:09 AM spelling
    Saturday, January 26, 2013 8:05 AM