Chapter 15

Data Recovery

Introduction to data recovery

Why you want to restore data from tape

This section describes why you want to restore data to the filer from tape.

Files were deleted from disk but backed up to tape

For example, if you inadvertently delete a file and want to restore the file, you can recover the file from tape.

Files are corrupted

If some files are corrupted, you can restore the subtree containing the files.

No disk slots are available for expansion

If the filer runs out of storage space, you can do the following tasks:

Back up the entire filer
Replace the current disks with disks of greater capacity
Set up volumes on new disks
Restore the filer from tapes

The entire filer is damaged and unusable

If the entire filer is damaged and unusable, call Network Appliance Technical Support to determine whether you can repair the filer.

If you can repair the filer but some files are deleted during the repair process, you need only restore the missing files. Otherwise, you need to reinitialize the disks and restore all files from tape.

Caution: Before initializing disks on your filer, call Network Appliance Technical Support for instructions. Initializing disks destroys all data on your disks.

When you do not recover data from tape

Recover a deleted file from tape only if you cannot recover the deleted file from any snapshot on the filer. If the file is in a snapshot, copying the file to the active file system is faster than recovering the file from tape.

Different methods for recovering data

The filer supports these methods for recovering data that was backed up by the filer's dump command:

Using the restore command on the filer to restore the file from a local or remote tape drive. If you use a remote tape drive, the host for the tape drive must support the rmt protocol.
Using the UNIX ufsrestore command on a client that supports the SunOS 5.x/Solaris 2.x ufsdump format.
Using third-party backup management software on a computer that supports the Network Data Management Protocol (NDMP) to restore data from a local or remote tape drive. For more information about NDMP, refer to Chapter 17, "Network Data Management Protocol (NDMP)."

Caution: Use the Solaris ufsrestore command only if your filer runs NFS exclusively. If your filer runs the CIFS protocol, do not use the Solaris ufsrestore command. Doing so results in data loss.

What data cannot be recovered

The restore command cannot recover data that was backed up by commands issued on other systems. For example, do not try to use the filer's restore command to recover a tape file created by the Solaris ufsdump command.

UNIX file permissions and Windows NT ACLs

A file recovered by the restore command has the same UNIX file permissions and Windows NT ACLs as it did when it was backed up. If you restore a file that has only UNIX file permissions to an NTFS qtree or volume, the file has no Windows NT ACLs. The filer uses only the UNIX file permissions on this file until you create Windows NT ACLs on it.

Scope of this chapter

This chapter describes how to use the filer's restore command for data recovery. It does not describe how to use data recovery commands or programs on other systems. Refer to the documentation accompanying the other systems for information about their data recovery commands or programs.

Part No. 210-02334
File: recover.htm
Last updated: 04/26/99 08:11:50