NetWare 5.1 Advanced Administration

Chapter 10: Backing Up Servers and Workstations

 

 

Objectives:

This chapter introduces various ways to make safety copies (backups) of network resources. The objectives important to this chapter are listed on page 10-1:

  1. Explain Backup Strategies
  2. Back Up Data with NWBACK32
  3. Restore Data with NWBACK32
Concepts:

The terminology used to describe the SMS (Storage Management Services) backup of a system is unusual. In the scenario at the beginning of the chapter, we are using SMS to provide the ability to make a backup of network data.

  • The host is a server that contains the software used to make the backup.
  • The target is a server or client workstation that contains data that will go into the backup.
  • The storage device is the actual medium used to receive the data being backed up.

This is a rather unusual use of the word target, but it makes sense in that the data to back up is the target of the software being run.

The list of possible targets should be examined:

  • the file system on a server
  • the DOS partition on a server
  • the NDS database
  • anything in the file system on a Windows or DOS workstation
  • GroupWise databases
Explain Backup Strategies

Three backup strategies, or schedules, are explained. You should know all three. First some terms:

  1. Full - a backup of all files in the target
  2. Incremental - a backup of target files that are new or changed since the last backup
  3. Differential - a backup of all files new or changed since the last Full backup

This needs more explanation. In a Full backup strategy, the entire target is backed up to tape every time we make a backup tape. This strategy consumes the most time and the most tapes to carry out a backup. To restore, we simply restore the most recent tape(s). This is the least time consuming strategy for restoring, but the most time consuming for creating backups.

The second method, Incremental backup, means that we start with a Full backup of the target, and then each successive backup tape we create only backs up the elements that are new or changed since the last backup was created. This means that successive backups will not always be the same length. Therefore, this is the least time consuming backup, but the most time consuming restore. To restore, we must first restore the last Full backup made, and then restore EVERY tape made since then, to ensure getting all changes.

The last strategy, Differential backup, also starts with a Full backup tape. Then each successive tape made will contain all the files changed since the last Full backup was made. This means that we will have to restore only one or two tapes in a restore operation. If the last tape made was a Full tape, we restore only that one. If the last tape made was a Differential tape, we restore the last Full tape, then the last Differential tape.

To keep them straight in your mind, remember that:

  • a Full backup copies everything
  • an Incremental backup copies everything different from the last backup
  • a Differential copies everything "different from Full". (Different from the last full backup.)

The time required to create backup tapes should be considered along with the time to restore a backup. When you consider the two concepts as two sides of the answer to a question (What method should I use?) the answer may be the most common choice: Differential. It is the best compromise in terms of backup time versus restore time. Note also, that all three methods require a full backup on a regular cycle. The recommendation is usually to run a Full backup tape weekly.

Rights and knowledge a user must have in order to carry out a backup:

  • to back up NetWare File Systems - Read and File Scan rights to the files
  • to back up NDS objects - the Browse object right and the Read property right to the Tree
  • to back up servers - the password on the host and target servers
  • to back up workstations - the password to any file or program that is password protected

Note that the appropriate Create right will be necessary to restore any of the backups made.

What rights are for each action? Mouse over the cells you think are needed.

Action
Rights Needed?
  Write Read Modify File Scan Access Control Create Erase Supervisor
Backup NetWare Files                
Restore NetWare Files                


Object Rights Create Browse Inheritable Rename Delete Supervisor
Backup NDS            
Restore NDS            
Property Rights Compare Read Inheritable Write Add Self Supervisor
Backup NDS            
Restore NDS            

Back Up Data with NWBACK32

The SMS system works by using two utilities:

  • NetWare Backup/Restore - a series of NLMs run on the server that actually do the backup or restore.
  • NWBACK32 - a utility that is run on a workstation as a control interface for the above NLMs

Terms are defined again for these utilities.

  • The host is defined as above, and we are given another detail about the target.
  • The target is the data that is being backed up or restored.
  • A target must have a TSA, a Target Service Agent, loaded in order to be backed up or restored. The TSA is a program that enables NetWare Backup/Restore to work with a specific type of target.
  • Parent and child are modified from their usual meanings. A parent, here, is a data set (a target) that contains other data sets. A child is a data set that does not contain other data sets.

We are given guidelines for using NetWare Backup/Restore. To summarize them:

  • Run NetWare Backup/Restore on a server, and have the tape drive on the same server.
  • You need about a megabyte of free space on the server's SYS: volume for temporary files created during the backup.
  • If you are running the backup unattended, make sure the tape is big enough.
  • Set append to "No" to make sure the tape in the tape drive is overwritten.
  • Do not run unattended if more than one tape is required. You will be prompted for the next tape.
  • Don't let just anyone run NetWare Backup/Restore.
  • Make sure the error and backup log files contain short and long names.
  • Allow lots of temporary file space on the target server.
  • Do not do anything else on the server during the backup process.
Restore Data with NWBACK32

There is a fourteen point process for using NetWare Backup/Restore to back up a server and a nineteen point (plus!) process for backing up a Windows workstation. A thirteen point procedure running a restore to either type of system is given as well. Examine these, but realize that many networks use third party software for making backups, and these procedures may not be useful in your situation.