# Faster Incremental Backups for NAS File Servers and Data Protection Volumes Using NetApp SnapDiff

Applies to: CIFS and NFS only

Commvault uses SnapDiff for faster incremental backups for regular backups of NAS file servers (network shares). SnapDiff is a NetApp feature that identifies which files changed between snapshots, so that backups do not have to traverse the entire file system to determine which files changed.

On NetApp storage arrays, all IntelliSnap backups of network shares use SnapDiff. You can also use SnapDiff for regular backups of network shares.

SnapDiff is especially effective when you have a large number of files that do not change a lot between snapshots.

Note

For NetApp storage array, the junctions between volumes are not supported.

## Support for NetApp Data Protection Volumes

You can use SnapDiff to perform faster incremental backups of the NetApp Data Protection (DP) volumes from the NetApp secondary array. This feature helps to protect secondary volumes (DP volumes) where access to the primary array is restricted.

To use this feature, do the following:

- Configure the sDPVolumePrefix additional setting on the NAS client. For information on how to configure an additional setting, see Adding a Setting for Servers and Server Groups.

- Mount the DP volumes and create the CIFS or NFS shares on DP volumes.

- Grant ‘Full Control’ access of the CIFS share on the destination array for an impersonated user.

- A latest snapshot of the secondary volume with prefix value as configured in the additional setting must be available on the DP volume before performing backup of the share using SnapDiff. Complete the snapmirror update on the destination array so that latest snapshot is available.

- Ensure that the access node has access to the destination array where the DP volume is present.

## NetApp SnapDiff Support

ONTAP version | SnapDiff v1 | SnapDiff v2 | SnapDiff v3 | Required Commvault version
--- | --- | --- | --- | ---
ONTAP 9.10.1 to 9.10.1 P10* | No | No | Yes | Upgrade your Commvault software to either of the following versions: CPR2022E (11.28) Maintenance Release 78 (Hotfix pack 78) CPR2023 (11.30) Maintenance Release 61 (Hotfix pack 61) CPR2023E (11.32) Maintenance Release 15 (Hotfix pack 15)
ONTAP 9.10.1 P11 and newer** | Yes | Yes | Yes
ONTAP 9.11.1 P7 and newer** | Yes | Yes | Yes
ONTAP 9.12.1 GA release and newer** | Yes | Yes | Yes
ONTAP 9.13.1 GA release and newer** | Yes | Yes | Yes

*To run SnapDiff v1 or v2 on this version, contact NetApp support to restore the APIs and contact Commvault support also. If back up jobs were already run on subclients and you upgraded ONTAP to either of these versions, then the first incremental scan will take longer as a TrueUp operation runs to gather file information. All the subsequent jobs will continue and use a recursive scan to collect file information.

**If back up jobs were already run on subclients and you want to run SnapDiff v1 or v2 or v3 for existing subclients after you upgraded ONTAP to either of these versions, then contact Commvault support.

Note

For the NetApp C-Mode system, use individual Storage Virtual Machine (SVM) clients for CIFS / NFS management. Do not use NetApp cluster for CIFS /NFS snapshot management.

## How SnapDiff Works

The first full backup job creates a baseline snapshot. A snapshot is created, data is scanned by traversing the file system, a snapshot is created, and then data is backed up from the snapshot.

Subsequent backups are incremental. SnapDiff identifies the data that changed by comparing the previous and current snapshots, without traversing the file system. Data is then backed up from the snapshot.

At the end of each job, snapshots created by the previous job are deleted from the array, and only one set of snapshots is retained on the array.

The scan operation that traverses the file system is used only in these cases:

- The snapshot from the previous job is not available

- The snapshot creation fails in the current job

- The SnapDiff operation fails

### Configuration Requirements for SnapDiff V2

1. Verify RPC is enabled on the vServer being cataloged or backup copied. Even if a cluster client is being cataloged, the vServer for the volume being cataloged or backup copied must have RPC enabled. On the file server, verify RPC is enabled on the vServer using the following commands:

       set advanced

       vserver snapdiff-rpc-server show -vserver $[vserver]

       vserver snapdiff-rpc-server on -vserver $[vserver]

2. Verify whether an NFS interface exists between the vServer and the Commvault MediaAgent. Specifically, confirm that there exists a vServer NFS interface on the file server node containing the volume being cataloged using the following commands:

       vserver nfs show -vserver $[vserver]

       network interface show -vserver $[vserver] -data-protocol $[nfs]

### Configuration Requirements for SnapDiff V3

1. Verify RPC is enabled on the vServer being cataloged or backup copied. Even if a cluster client is being cataloged, the vServer for the volume being cataloged or backup copied must have RPC enabled. On the file server, verify RPC is enabled on the vServer using the following commands:

       set advanced

       vserver snapdiff-rpc-server show -vserver $[vserver]

       vserver snapdiff-rpc-server on -vserver $[vserver]

2. Verify whether an NFS interface exists between the vServer and the Commvault MediaAgent. Specifically, confirm that there exists a vServer NFS interface on the file server node containing the volume being cataloged using the following commands:

       vserver nfs show -vserver $[vserver]

       network interface show -vserver $[vserver] -data-protocol $[nfs]

3. Verify that the cluster array login is authorized for REST, HTTP, and SSL. For more information on setting up a NetApp cluster login.

   1. To enable REST API based authorization to the cluster array, run the following commands:

          vserver services web access show -vserver $[vserver] -name $[rest] -role $[role]

          vserver services web access create -vserver $[vserver] -name $[rest] -role $[role]

   2. To enable HTTP and SSH based authorization to the cluster array, run the following commands:

          security login show -vserver $[vserver] -user-or-group-name $[user] -application $[http]

          security login create -vserver $[vserver] -user-or-group-name $[IntelliSnapUser] -application $[http] -authentication-method $[password] -role $[role]

          security login show -vserver $[vserver] -user-or-group-name $[user] -application $[ssh]

          security login create -vserver $[vserver] -user-or-group-name $[IntelliSnapUser] -application $[ssh] -authentication-method $[password] -role $[role]

   3. To enable the SnapDiff and license APIs for the cluster array, run the following commands:

          security login role show -vserver $[vserver] -role $[role] -cmddirname "$[snapdiff]"

          security login role create -vserver $[vserver] -role $[role] -cmddirname "$[snapdiff]" -access $[all]

          security login role show -vserver $[vserver] -role $[role] -cmddirname "license"

          security login role create -vserver $[vserver] -role $[role] -cmddirname "$[license]" -access $[all]

4. Note: For SnapDiff v3, the array management entries for the vServer must have tunneling to the selected cluster. SnapDiff V3 requires security key authentication that is supported only on the cluster interface.

## Related Topics

- Verify that your environment meets the system requirements for SnapDiff.

- To compare the performance of backups with SnapDiff to backups without SnapDiff, see Metrics for NAS File Server Backups with SnapDiff.

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