During backup operations, Druva utilizes Microsoft Volume Shadow Copy Service (VSS) to create shadow copies of server data. These shadow copies are then used by Druva to ensure consistent and reliable backups.
By default, VSS stores shadow copies on the same volume from which the data is being backed up. This can lead to:
Increased I/O operations on the source volume.
Low disk space issues on the same volume.
Higher I/O wait times, potentially impacting server performance.
To mitigate these risks, it is recommended to configure VSS to write shadow copies to a separate NTFS volume.
Why Use a Separate Volume for VSS Shadow Copies?
Reduces load on the source volume during backups.
Improves backup performance by isolating read/write operations.
Prevents space exhaustion issues on critical data volumes.
Helps avoid VSS failures due to insufficient disk space.
📝 Note
While you can configure VSS to write shadow copies to any existing volume, it’s best practice to assign a dedicated NTFS-formatted volume solely for this purpose.
Prerequisites
Before you configure VSS:
Ensure the target volume (where shadow copies will be written) has sufficient free space.
The target volume must be formatted with NTFS.
Assign enough space for shadow copies based on your backup requirements.
Steps to configure VSS shadow copy storage location
Open the command prompt as an administrator.
Navigate to C:\Windows\System32.
Locate cmd.exe.
Right-click and select Run as Administrator.
( Optional ) View Current VSS Configuration
To check the current storage association for shadow copies, run:
vssadmin list shadowstorage
This command lists the source and target volumes currently used for shadow copy storage.Add a New Shadow Copy Storage Association.
Run the following command to configure a new shadow copy location:
vssadmin add shadowstorage /for=<source_volume> /on=<target_volume> /maxsize=<maximum_size>Parameters:
/for=The source volume where the original data resides (for example, d:)/on=The target volume where shadow copies should be stored (for example, c:)/maxsize=The maximum space allocated for shadow copies on the target volume (for example, 90%, 20GB, etc.)
Example command:
vssadmin add shadowstorage /for=d: /on=c: /maxsize=90%In this example, shadow copies for the D: drive will be stored on the C: drive, using up to 90% of the C: drive available space.
Verify the configuration.
After successful execution, you’ll see the following confirmation message:Successfully added the shadow copy storage association.You can rerun vssadmin list shadowstorage to verify the updated configuration.
For optimized Druva backups, it's recommended to redirect VSS shadow copies to a dedicated NTFS volume. This practice significantly boosts backup efficiency, minimizes performance issues, and helps guarantee successful backups. Just be sure to consistently monitor this volume's disk space and adjust it as needed.