Restore Data - Tru64 File System iDataAgent - Full System Restore

Topics | How To | Full System Restore | Related Topics

Overview

The difference between a normal restore and a full system restore is the severity of the problem. Normally, if data is lost or removed, it is recovered from the archives using the normal restore procedures. However, when a normal restore operation cannot correct a software and/or hardware corruption problem, some additional changes may be required.

When the root file system is lost, a full system restore is required.

On a Tru64 system, this operation involves using the btcreate utility to create a bootable Standalone System (SAS) kernel on tape.

The full system restore procedure for Tru64 assumes (and recommends) that you use the btcreate utility software prior to the deployment of the Tru64 File System iDataAgent. For more information on using the btcreate utility, see Prepare for a Full System Restore.

Prepare for a Full System Restore

Before You Begin

The full system restore procedure for Tru64 assumes (and recommends) that you use the btcreate utility software prior to the deployment of the Tru64 File System iDataAgent. The btcreate utility creates a bootable Standalone System (SAS) kernel on tape. The SAS kernel has a built-in memory file system (mfs). This file system contains the commands, files, and directories needed to restore the system image.

The btcreate utility prompts you for information. Default answers, if applicable, are enclosed in square brackets ([]). To select a default answer, press Return at the corresponding prompt. Enter q at any prompt to exit the utility and to discard any information that you enter up to the exit point.

Since the btcreate utility will prompt you for the following information, you may want to identify these items and have them available prior to executing this procedure:

Name of the kernel configuration file
Disk partition to contain the SAS kernel
Tape device to use for backup operations
List of file systems to back up
List of files and directories to back up

After identifying the above information, you may continue on to the procedure to prepare for a full system restore below.

To prepare for a full system restore:

Enter the following at the prompt to start the btcreate utility:

# cd /usr/sys/bin
# ./btcreate
You are asked if you want to continue. Select y.

Do you want to continue (y/n) [y]:
Enter the name of the kernel configuration file to be used by the btcreate utility.
This file is located in the /usr/sys/conf directory, and it defines the run-time behavior of the kernel. The btcreate utility uses this file to build the SAS kernel.

Enter the name of the kernel configuration file [GAZOO]:
If you want to save space on the disk and build the miniroot file system (MFS) on a memory file system (mfs), enter y for the following question. An MFS file system is a UFS file system in virtual memory. If you want to create the miniroot file system on the disk, enter n .

Do you want to use a MFS file system? (y/n) [y]:
The btcreate utility requires 70120 (512 blocks) of disk in the /usr file system for the temporary files that are created during bootable tape creation. If you have space constraints in the /usr file system , you can use disk space in file systems other than the one on which /usr/sys is located. When this flag is used, all necessary temporary space needed by btcreate will be used in the specified directory.

For the following question, enter y if you want btcreate to use the space available in /usr/sys. Enter n if you want btcreate to use some other area for temporary files.

Do you want temporary files to be created in /usr/sys ? (y/n) [y]:
The SAS kernel and file systems are backed up to a no-rewind tape device. Specify this tape device (for example, tape2_d1).

Enter the name of the tape device [tape0_d1]: tape2_d1

Momentarily, the following message appears:

Verifying tape... Done.
Specify which file systems you want to include on the tape device. Each entry consists of the device name, mount point, and file system type separated by a space or tab as follows.

            device_name           mount_point          fs_type

To help with your selections, here is some example information about a local file system:

         root_domain#root        /               advfs
     usr_domain#usr            /usr            advfs
     usr_domain#var            /var            advfs
     new_root_domain#root      /root           advfs
     new_usr_domain#new_usr    /root/usr       advfs
     new_usr_domain#new_var    /root/var       advfs

Per the prompts, start to enter your selections. Be sure to press Return after each entry or at the prompt to end your input. After you enter each selection, you are informed that the selection is selected for backup.

Enter your selection:
root_domain#root / advfs
root_domain#root / advfs selected for back up.

Enter your selection:
usr_domain#usr /usr advfs
usr_domain#usr /usr advfs selected for back up.

Enter your selection:
usr_domain#var /var advfs
usr_domain#var /var advfs selected for back up.

Enter your selection:
Have you completed your selections (y/n) [y]:
Optionally, add files and directories to the miniroot file system. Each entry consists of two fields separated by a space or tab as follows.

file destination

The first field specifies the absolute pathname of the file or directory on the currently running system. The second field specifies the absolute pathname on the miniroot file system.

If you do not make an entry, you will be asked to confirm your decision.

Press the Return Key after each entry or at the prompt to end input.
Enter your selection:
You did not select a file or directory to back up.
Is this correct (y/n) [y]:
No files will be added to the miniroot file system.
A series of messages that summarizes your selections is displayed. You can accept or modify any selection. If you want to exit the utility and discard all of the information that you entered, enter q at the prompt. For example:

Kernel Configuration File specified : /usr/sys/conf/GAZOO
Disk Partition : mfs
Tape Drive : tape2_d1

File systems included : yes
Miniroot customizations : no
The following file systems were specified for backup:

Device_Name         Mount_Point        File_Type          Size
root_domain#root /                  advfs              322712
usr_domain#usr      /usr               advfs              1129584
usr_domain#var      /var               advfs              160394

.....
.....
.....
.....

vdump: Status at Fri Sep 14 15:44:58 2001
vdump: Dumped 78223643 of 78214988 bytes; 100.0% completed
vdump: Dumped 356 of 356 directories; 100.0% completed
vdump: Dumped 1827 of 1824 files; 100.2% completed
vdump: Dump completed at Fri Sep 14 15:44:58 2001
Dump finished.
Rewinding the tape.
btcreate.log file has been created on /var/adm directory.

End of system image creation on tape.

Perform a Full System Restore

Try to avoid the unconditional overwrite of the root directory on a live file system. This is a mechanism that allows an unconditional overwrite of open files in the root directory (/) on a live file system. Performing such a restore can result in an inconsistent system that may also fail to boot. Use this option AT YOUR OWN RISK.

Before You Begin

The full system restore procedure for Tru64 assumes that you have previously used the btcreate utility to create a bootable Standalone System (SAS) kernel on tape. See Prepare for a Full System Restore for more information.

Required Capability: Capabilities and Permitted Actions

To perform a full system restore:

Boot the tape to restore the system . To do this, issue the following command from the SRM console prompt:

>>> boot mka300 -fl "nc"

Parameter "mka300" is the tape device, and digit "3" within this parameter is the SCSI ID of the tape drive.
Once the system is booted, go to the CommCell Console to perform a default restore using your default values. Specifically, right-click the backup set, click All Tasks, click Restore, enter / as the path to restore from, and select "restore to same paths".

Do not select Unconditional Overwrite from the Restore Options dialog box.
When restoring encrypted data, refer to Data Encryption.
Click OK to start the restore.
Verify that the restore operation has completed successfully. Then reboot the computer. The system should boot to the newly-restored root.