Frequently Asked Questions - NAS iDataAgent

What are Two-Way restores?

A two-way restore consists of restoring the data to a file server from a locally attached (or SAN-connected) library.

The following restore methods are supported:

Restoring to the same location on the file server from where the data was backed up.
Restoring to a different volume or folder on the same file server.

What are Three-Way restores?

A three-way restore consists of restoring the data to a different file server or computer. A three-way restore enables more than one file server to share a library allowing the restore of data to a file server which may not have a locally attached library.

The following restore methods are supported:

Restoring to a different file server
Restoring from a library attached to a MediaAgent
Restoring to a Windows or Unix computer (using File System Restore Enabler)

Can I filter Subclient Content on All NetApp Clients?

No. Subclient filters are supported only for NetApp 7-mode clients. Subclient filters are not supported for NetApp C-mode clients.

Can I Browse for Subclient Content on All NetApp Clients?

No. You can browse for subclient content only on NetApp 7-mode clients. You cannot browse for subclient content on NetApp C-mode clients.

Can I restore block based backups to multiple ONTAP releases?

No. You can restore block based backup images up to one or two major ONTAP releases. It is highly recommended that you consult the NetApp documentation for limitation on block based backup restores.

Can I perform block based backups on file servers with versions prior to ONTAP 8.0?

It is required that you get an approval from NetApp in order to perform a block based backup on a file server running an ONTAP version prior to 8.0.

Can I enable the Image Backup Set option on a SnapVault Copy?

Yes, you can enable the Image Backup Set option (for SnapMirror to Tape) on a backup set containing the SnapVault copy. However, the image backup of the SnapVault copy will not exactly match the primary (source) volume. For example, the non-qtree data on the primary volume will be in a qtree on the SnapVault copy; the SnapVault copy may also contain data from other primary volumes.

Can I use a MediaAgent-attached (NRS) drive pool to restore data that was backed up using an NDMP drive pool?

No. To restore NAS data, you must use the same drive pool type that you selected during backup. For example, if a drive pool associated with the NDMP Remote Server (NRS) was used to perform the backup, you should also select an NRS drive pool during restore.

Are non-Image Browse operations of Celerra data supported for Direct Access Restores?

Yes. Browse operations for EMC Celerra are always non-image browse operations. Even if an image browse is performed, the restore will be a non image restore.

How do Direct Access Restores behave when restoring large data?

The nRESTORELIMIT registry key is automatically created during installation to control the behavior of large direct access restores.

This key specifies how many files/directory names can be sent in a single restore request; between each request, the tape will be positioned to the start of the first tape. For example, performing a direct access restore of a tree with 24,000 files/directories would require three restore requests (using the default value of 8192 per request) to be sent to the file server.

When should I perform a Direct Access Restore?

It is hard to define when a Direct Access Restore provides better performance as each environment is different and has many variables that can affect restore efficiency. Use the following guidelines to determine if this restore operation is appropriate for your environment:

If the data to be restored is less than 30-40% of the backup, it is recommended to perform a direct access restore.
For three-way restores, as it involves more overhead processing between the library and the file server, it is recommended to perform a non-direct access restore even if the percentage of the backup being restored is under 30%.

If you are not using direct access restores, restore performance is still optimized where possible. For instance, if the most recent copy of the data that you want to restore was backed up by an incremental or differential backup, the restore only reads the archive file from that differential or incremental backup, instead of reading the archive files back to the last full backup.

Why Can I No Longer Run Incremental Backups?

Most file servers have a limit to the number of incremental backups, except Celerra, BlueArc, Hitachi, ONStor, and Isilon. Other supported file servers allow incremental backups with the following limitations:

After a full backup, a maximum of 9 incremental backups can be run sequentially. At this point, a full or differential backup must be run.
After a differential backup is run, you can run 8 more incremental backups before performing another full or differential backup.

Can I backup data to a local tape drive for a NetApp vFiler?

No. You can backup data on a NetApp vFiler by adding the vFiler as a NAS client.

What is Tape Silvering?

Tape silvering is the process of shipping a physical copy of the source data to a destination site. This is useful for large file systems as it saves time and resources and also avoids transferring the file system over the network. Refer to the EMC Celerra documentation for more information.

Can I perform the block based backup for an On-Demand backup set?

You can perform the block backup for an On-Demand backup set. You must configure an On-Demand Backup Set for block backup. However, once you configure the On-Demand Backup Set for block backup, you cannot change the configuration and perform the regular backup for the the On-Demand Backup Set.

Can I perform incremental or differential backup for a block based backup set?

When you create a backup set for block based backup, you cannot perform incremental or differential backups using that backup set. You can perform the full backup of the backup set.

When does a Non-Full Backup Automatically get Converted to a Full Backup?

A non-full backup is automatically converted to a full backup in the following situations:

First backup of the subclient.
Re-associating a subclient to another storage policy.
Promote a secondary storage policy copy that is not synchronized with a primary copy (for all the subclients of a storage policy).
If a backup job within the most recent backup cycle is pruned or disabled from a primary copy.
Adding a new content path to the subclient.
If you switch from a SnapProtect backup to a traditional backup or vice versa.
CommCell Migration operation.

How Do I Setup Deduplication for NAS NDMP Backups?

Deduplication of NDMP data is supported for NetApp and EMC Celerra storage arrays to disk libraries attached to a CommVault Deduplication MediaAgent. When backing up to disk libraries attached to the MediaAgent, the NDMP backup data will traverse the network and be written and deduplicated to the disk library.

For all other NDMP vendors, Deduplication is supported but the savings may not be as high. To achieve higher Deduplication savings of these backups, it is recommended to move backups from NDMP to a mounted file system backup using the data residing on CIFS or NFS mount using the File System iDataAgent. However, before moving to CIFS or NFS file systems, make sure to verify the data transfer rate over CIFS or NFS as low transfer rate may result in slower backups. This configuration also supports Synthetic Full backups and DASH Copy.

Can I use a MediaAgent-attached drive pool to restore data that was backed up using an NDMP drive pool?

No. To restore NAS data, you must use the same drive pool type that you selected during backup. For example, if an NDMP drive pool was used to perform the backup, you should also select an NDMP drive pool during restore.