Chapter 14

Data Backup

Introduction to data backup

Meaning of data backup

Data backup means copying data from disk to tape. While the filer dump command enables you to copy data to standard output, this chapter mainly discusses how to copy data to tape.

Why you want to back up data from disk to tape

The following list describes the reasons for backing up data from disk to tape:

You can restore data from tape if an application or a user inadvertently corrupts or deletes files that cannot be recovered from snapshots.
You can store the backup tapes at an off-site archive to protect the data against natural disasters.
After you reinstall the file system on the filer (for example, for migrating to larger disks or for converting a single-volume filer to a multivolume filer), you can restore data from tape.

Different methods for backing up the filer

The filer supports three backup methods:

Using the filer dump command.
Using an application on a computer that supports the Network Data Management Protocol (NDMP). For more information about NDMP, refer to Chapter 17, "Network Data Management Protocol (NDMP)."
Using commands or a non-NDMP-compliant application from an NFS or a CIFS client.

Caution: If you use the tar or cpio command on an NFS client to back up the filer, be aware that some versions of these commands fail with file systems that contain long path names, unusual file names, or hard links.

Comparison of backup methods

The following table compares the different backup methods.


Filer dump command	NDMP applications	Commands or non-NDMP applications on NFS or CIFS client
Initiate the backup session from the filer console or from a trusted host through `rsh`.	Initiate the backup session from the computer running the NDMP application.	Initiate the backup session from the NFS or CIFS client.
Back up any files or directories.	Back up any files or directories.	Back up the files or directories that are mounted or shared by the client.
Back up data to tape drives attached to the filer being backed up, to another filer, or to another computer.	Back up data to tape drives attached to the filer being backed up, to the computer running the NDMP application, or to another filer.	Back up data to tape drives attached to the filer or to the client if the client supports the `rmt` protocol.
Preserve both NFS and CIFS attributes.	Preserve both NFS and CIFS attributes.	If backup is initiated on an NFS client, CIFS attributes are not preserved.

Scope of this chapter

This chapter describes how to use the dump command to back up the filer. This chapter does not describe how to use commands or applications on an NFS or a CIFS client to back up the filer.

This chapter also does not discuss how to enable NDMP on the filer so that you can use an NDMP-compliant application for backing up the filer.

Part No. 210-02334
File: dump.htm
Last updated: 04/26/99 08:11:48