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Druva Documentation

Set VSS to write shadow copies to a separate NTFS volume

On a Windows server, Phoenix instructs Microsoft Volume Shadow Copy Services (VSS) to create shadow copies of server data during backup. Phoenix uses these shadow copies to create a backup of your server data. By default, VSS writes the shadow copies of a volume to a location on the volume itself. This can result in high I/O operations on the volume because VSS writes shadow copies and Phoenix reads the shadow copies from this same volume. Additionally, the volume might experience low disk space problems and a high I/O wait time. To avoid these issues, we recommend that you create a separate volume and configure VSS to write shadow copies to this volume.

Note: You can configure VSS to write shadow copies to existing volumes. However, to avoid issues such as high I/O wait time and low disk space on these volumes, we recommend that you assign a volume for shadow copies, and then configure VSS to write shadow copies of other volumes to this volume. 

Before you begin

Before you begin, ensure that the volume to which you want VSS to write shadow copies has sufficient free space. We recommend that you configure VSS to write shadow copies to a separate volume assigned for this purpose. 

Note: Ensure that you set the file system of this volume to NTFS. 

To configure VSS

  1. Open the command prompt as an administrator.
    1. Browse to C:\Windows\System32.
    2. Right-click cmd.exe, and click Run as administrator
  2. (Optional) To determine the current location to which VSS stores shadow copies, run the following command:
vssadmin list shadowstorage
  1. To configure VSS, run the following command:
vssadmin add shadowstorage /for=<source volume>/on=<target volume>/maxsize=<space assigned on target volume>

For example, if you want to store shadow copies of folders on D: drive to the C: drive, and you want to allow VSS to use up to 90% of the free disk space on C:, the command might look like this: 

vssadmin add shadowstorage /for=d: /on=c: /maxsize=90%

After successful execution of the command, the following message appears on the command prompt: 
Successfully added the shadow copy storage association.

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