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Welcome to Lesson 11, Day 2- Chapter 10 - Network Administration and Support

Course Notes

Lesson 11 Notes - Cont'd

Managing Network Data Security

When deciding on a network security plan, it is important to rememberthat all situations are different and that the same security measures are not necessary in all instances.

Security Models

• Physical security may be as simple a installing the servers in a locked room and ensuring that only authorized personnel have access.
• The data security models roughly correspond to the network models, i.e., peer-to-peer networks use share-oriented security whereas server-based networks use user-oriented security. This should be considered in all phases of network planning. The level of security required has a large impact on the network operating system chosen.

Implementing Security

Any good security plan must involve user training. The more a user understands why you have implemented a particular system, the less likely they are to cause problems. For example, if a user doesn’t understand that their password has to be changed every 60 days, then, when they can’t logon because their password has expired, they will become frustrated and come to the administrator. However, if the user does understand that the security plan requires them to change their password, when they receive the message from the server telling them its time, they will do so willingly.

Maintaining Security

In order to maintain security, the security plan must be reviewed on a regular basis. Necessary changes to the plan and any additional user orientation or training on new procedures should be undertaken immediately to "close any holes" that are uncovered.

Avoiding Data Loss

One of the key aspects of networking, and, indeed, one of the major selling points, is the ability to protect data. Aspiring network administrators are often able to convince their bosses that a network is in order by showing them that the chances of losing a document are greatly reduced when a network is installed.

• Tape Backups - Regular and Often
  • Full backup - copies all selected files to tape.*
  • Incremental backup - copies only those files changed since the last full or incremental backup.*
  • Differential backup - copies all files changed since the last full backup - does not reset the archive bit.*
  • Copy backup - copies selected files to tape without resetting the archive bit
  • Daily backup - copies all files changed the day the backup is made
    * Most useful as a part of a regular back-up schedule.
  • A backup log is very important when it comes to disaster recovery. By keeping a log, an administrator can easily see which tapes contain the data he needs and so he will not waste time searching through tapes. Many new backup programs, such as ARCserve, perform this function automatically.
  • Test restorations to ensure the backups are running properly. It would be of no use to anyone if, when the hard drive in the server crashed, the data on the full backup could not be restored.ally.
  • It is very important to create a backup schedule and stick to it. Make sure that everyone responsible for the backups knows what needs to happen and when. It is often best to assign this task to one person to ensure it is done the same way every day.
• Repairing or Recovering Windows Systems
  • Windows NT and Windows 2000 contain repair utilities and features like the Emergency Repair Disk (ERD), the recovery console, fixmbr, fixboot, and diskpart that are available for use by network administrators to aid in data recovery.
• Uninterruptible Power Supply (UPS)
  • UPSs can prevent data loss by ensuring the server has enough power to shutdown gracefully.
  • A UPS is also able to condition the power coming from the wall outlet and provide surge protection.
  • Many UPS systems provide connections for 10BaseT, RJ-45, or RJ-11 connections to prevent surges from damaging network cards, ISDN interfaces, and modems.
• Fault-Tolerant Systems
  • Disk mirroring and duplexing are two methods often used prevent data loss. With disk mirroring, if the hard drive controller fails, data is still lost. However, with duplexing, if the primary controller fails, the secondary drive and controller still ensure that data is safe.
  • Redundant Arrays of Inexpensive Disks (RAID) - Levels: 0 - 5
    • Disk mirroring and disk duplexing are RAID level one.
    • Disk striping with parity is actually RAID level 5. This system insures data against data loss by writing parity information for the data written on a different drive than the data is on. When a drive fails, this parity information can be used to reconstruct the data. Windows NT and Windows 2000 operating systems will perform disk striping with parity without extra adapter cards or software. This is one unique feature of Windows NT.
    • When using RAID 5, all partitions in the stripe set must be the same size, and the equivalent of one disk is used for parity information. For example, if a stripe set consists of six 600 MB drives, the total usable space is 3 GB (5x600) while the parity space will equal 600 MB. Parity information is not located on a single hard drive.
  • Benefits of various fault-tolerant systems:
    • Disk mirroring is less expensive, but makes less efficient use of the drive space available.
    • Disk striping with parity makes more efficient use of the drives available, but requires many more resources then mirroring.
  • Intellimirror - Intellimirror is a client/server application that runs on Windows 2000 machines and creates a “smart back-up copy” of a system on an Intellimirror server. This application gives users access to all files and settings regardless of which system they are using to attach to the network.

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Lesson 11, Day 2 - Case Assignment

Your network has three servers and 15 workstations. You have been tasked with implementing a backup policy that will ensure against data loss, provide a fast backup, and provide the fastest recovery in the event of a failure. Outline a backup policy to suit your needs.