CHAPTER 9 System Backup and Restoration, Disk Cloning

Transcription

1 CHAPTER 9 System Backup and Restoration, Disk Cloning Learning Objectives After completing this lesson, you should be able to: i. Explain the method of doing data backup and restoration. ii. Describe the backup and restoration process. iii. Explain the purpose of disk cloning. iv. Describe the features of disk cloning and post-cloning operations. System Backup and Restoration System Crash When a software application running on a computer system crashes, it can be reinstalled. But when the computer system crashes, the computer won t be bootable and cannot be used. The negative effects of a system crash include: Data are lost and gone forever. Most or all businesses cannot afford to lose their data. For example, a bank needs its data on customers in order to keep functioning normally. Without these data, the bank can close shop. Money is lost as business operation has to stop. Customer confidence in business may be affected. Customers may decide to go to leave if they are worried about more crashes. SY2006FP: Computer Essentials Page 9-1

2 To minimize the damages from a system crash, all computer systems must be backed up. In the event of a system crash, it should be restored in the shortest time possible. Backup refers to the duplication of system and data files onto magnetic tape or other offline mass storage media. Types of Backup There are three types of backup: Full-backup This method involves making a full copy of all the system, application and data files. It is the best method. But it is time-consuming and expensive Incremental backup This method involves backing up only files that have changed after the last backup It is faster and cheaper than Full Backup method. But it is time-consuming to restore data Differential backup This method involves backing up only files that changed after the last full-backup. Time taken is in between full-backup and incremental backup Restore time is faster than the other methods. Frequency of Backups How often should backups be done? The frequency can be, Daily If applications and data change quite a lot every day, such as for banks, stock exchanges, it would be best to perform backups on a daily basis if possible. Weekly If applications and data change quite a lot only over a few days, weekly backups would be acceptable. Monthly If applications and data have little changes, monthly backups would be enough. Who performs backups in a company? It can be done by an authorized staff, or it can be outsourced to a Backup Service Agency. SY2006FP: Computer Essentials Page 9-2

3 Windows 7 Backup In Windows 7, you can create a system image. This is a copy of Windows and copies of your programs, system settings, and files. It is then stored in a separate location from the original programs, settings, and files. You can use this image to restore the contents of your computer if your hard disk or entire computer ever stops working. If you're using Windows Backup to back up your files, you can have a system image created each time your files are backed up. The files can be saved on a USB flash drive, CDs, DVDs, or a hard drive. The system image must be saved on a hard drive. By default, the system image only includes the drives required for Windows to run. If you want to include additional drives in the system image, you can manually create a system image. If you manually create a system image, it can be saved on a USB flash drive, CDs, DVDs, or a hard drive. A system image is an exact copy of a drive. By default, a system image includes the drives required for Windows to run. It also includes Windows and your system settings, programs, and files. You can use a system image to restore the contents of your computer if your hard disk or computer ever stops working. Apple OS Backup There are four backup options for Mac OS X 10.7 Lion, namely, Time Machine Backup Once set up, it automatically makes hourly backups for the past 24 hours, daily backups for the past month, and weekly backups for all previous months. The oldest backups are deleted when your backup drive is full. External Drive Backup This option allows backup to be done on an external drive. icloud Apple provides a cloud storage at icloud for users to backup their data. Safekeeping of Backup Devices Once backup has been done, the backup devices (except for cloud storage) has to be kept in a safe place. The devices must safe from, thieves fire physical damage SY2006FP: Computer Essentials Page 9-3

4 water System Restoration When disaster hits and a system goes down, it must be restored using the backup disks. System restoration is the process of bringing offline storage data back from the offline media and putting it on an online storage system such as a file server. Each OS has its own procedure for restoring a corrupted or crashed system. Windows OS has System Restore. Apple OS has OS X Recovery. These help the user restore computer's system files to an earlier point in time. Usually, it is best to restore your computer to a restore point that was created just before the date and time when you started noticing problems. For Windows 7, restoration from a system image is a complete restoration you can't choose individual items to restore, and all of your current programs, system settings, and files are replaced with the contents of the system image. In contrast, Windows Backup allows individual files and folders to be restored. When you set up Windows Backup, you can let Windows choose what to back up, which will include a system image, or you can select the items that you want to back up and whether you want to include a system image. SY2006FP: Computer Essentials Page 9-4

5 Disk Cloning To clone an object means to make a copy of that object. Disk cloning is the process of copying the contents of one computer hard disk to another disk, or to an "image" file. The objective to disk cloning include, Archiving of data Allow lost or damaged data to be recovered Duplicate a hard disk with the image of an existing system Disk cloning involves copying hidden and in-use files. Normal copy functions of OS cannot do that. Special disk cloning software are needed. Disk Cloning Software Some of the commercial software available are : Acronis True Image Paragon Backup and Recovery Clonezilla PING (Part Image is Not Ghost) SY2006FP: Computer Essentials Page 9-5

6 The common features of these software for disk cloning include: Backup Options - Disk Backup (backup the whole disk) - Partition Backup (backup selected partition/s only) - System Backup (backup system files only) - File and Folder Backup (backup data files and folders only) Levels of file compression - high - medium - low - none Computer files can be compressed to reduce its size. Smaller files means less storage space is needed on a storage device. High compression of data will result in a need for less storage space for files, but backup will take a longer time. No compression of data will need more storage space, but backup will be faster. Encryption Encryption is the process of encoding information so that only authorized parties can read it. An encrypted computer file must be decrypted to be read. A key is needed for decryption. SY2006FP: Computer Essentials Page 9-6

7 Backup Policy Security Technology Department Chapter 9 A company may state its backup policy clearly to ensure that computer personnel know what to do. An example of a policy is shown here. Backup Policy (Sample) 1. Overview This policy defines the backup policy for XYZ Company. The systems for backup are typically servers but are not necessarily limited to servers. Servers expected to be backed up include the file server, the mail server, and the web server. 2 Purpose This policy is designed to protect data in the organization to be sure it is not lost and can be recovered in the event of an equipment failure, intentional destruction of data, or disaster. 3. Scope This policy applies to all equipment and data owned and operated by the organization. 4. Definitions i. Backup - The saving of files onto magnetic tape or other offline mass storage media for the purpose of preventing loss of data in the event of equipment failure or destruction. ii. Archive - The saving of old or unused files onto magnetic tape or other offline mass storage media for the purpose of releasing on-line storage room. 5. Backup Timing Full backups are to be performed nightly on Monday, Wednesday, and Friday. If for maintenance reasons, backups are not performed on Friday, they shall be done on Saturday or Sunday. 6 Disk Storage There are to be 4 disks for backup. One disk is to be used for Monday, one for Wednesday, one for Friday. One disk shall be used for monthly backup. 7. Monthly Backups Every month a monthly backup shall be made using the latest backup disk. 8. Responsibility The IT department manager shall delegate a member of the IT department to perform regular backups. SY2006FP: Computer Essentials Page 9-7

8 9. Testing The ability to restore data from backups shall be tested at least once per month. 10. Data Backed Up Data to be backed up include the following information: User data stored on the hard drive. System state data The registry Systems to be backed up include : File server Mail server database server web server 11. Restoration Users that need files restored must submit a request to the help desk. Include information about the file creation date, the name of the file, the last time it was changed, and the date and time it was deleted or destroyed. 12. Disk Storage Locations All backup disks shall be stored in an adjacent building, placed in a fireproof safe. Monthly backup disk shall be stored in a remote facility, placed in a fireproof safe. SY2006FP: Computer Essentials Page 9-8