Backups

[sammy]

TEPOA CUG
Backups
People Helping People Use Computers
By Bill Horton

Why do I need a Backup?
• Many have said “I don’t need a backup! All I have is e-mail and a few pictures.”
• When the system crashes I hear “I just want ______ from my computer.”
(You fill in the blank. It could be phone numbers, addresses, pictures of someone who just died, your biography or memoirs, a recipe, or even a game you enjoyed.)

Definition
• Backup or the process of backing up refers to making copies of data so that these additional copies may be used to restore the original after a data loss event. These additional copies are typically called "backups."

Why Have Backups?
• Data loss is very common. 66% of internet users have suffered from serious data loss.
• Backups are useful primarily for two purposes.
– The first is to restore a computer following a disaster (called disaster recovery).
– The second is to restore small numbers of files after they have been accidentally deleted or corrupted.

What is a Disaster?
• Computer Failure or Destruction
– Due to Accident/Fire
– Internal computer failure
– Backup failure
• Hard drive failure
– Controller failure
– Head Crash
– Corruption of boot sectors or directory
– Magnetic interference

Hard Drive - Platters
How do files get corrupted?
• Wearing of the disk surface.
• Magnetic effects
• Dirt/Dust contaminates disk surface
• Virus/Malware

Small Defects Can Grow
• Damage of this type is usually confined to a single sector for any one event.
• Since hard drives storage is very large and most critical parts are relatively small, failure may even be in an unused area.
• To prevent files from using damaged areas do a disk check, which will block off damaged sectors so they will not be used.

Check Disk
• Windows has a utility to check the hard drive
– Files - verifys file record and master file table
– Indexes – NTFS directories
– Security Descriptors – file ownership
– Sector Check – Check for bad sectors
• The utilities will block bad sectors from use
• The utilities will save orphaned files
• This can take a long time to run
One Way to Run a Disk Check
• Go to the start menu
• Left click on “My Computer”
• Right click on the selected drive
• Select “Properties” from the popup menu
• Select the “Tools” tab
• In the Error-checking box click on “Check Now…”
• Select both check boxes
• Click the Start button

How Long Can a Hard Drive Last?
• Normally they will last as long as the computer
• When you perform a disk check, a report is generated which will show the number of bad sectors. If this number becomes a significant percentage of the drive, action should be taken to replace the hard drive.

What are Backup Requirements?
• A backup system contains at least one copy of all data worth saving.
• Organizing this storage space and managing the backup process is a complicated undertaking (backup schemes)
• There are many different types of data storage devices that are useful for making backups
• You may need to provide geographic redundancy, data security, and portability

Backup Schemes
• Jon’s Backup Scheme for his portable.
– An External Hard drive that matches the computer Hard Drive
– Create a mirror image of the computer hard drive on the external hard drive (at a given date)
– If there is a disk failure the computer hard drive can be removed and the external hard drive can be put in the computer. This restores everything as it was on the back up date.
– This gets the system up an operating very rapidly

Unstructured Backup
• An unstructured repository may simply be a stack of CD-Rs/DVD-Rs media with minimal information about what was backed up and when. This is the easiest to implement, but probably not the best to achieve a high level of recoverability.
• With the size of the new hard drives, many disks may be needed.
Full + Incremental Backup
• A Full + Incremental backup scheme aims to make storing several copies of the source data more feasible. At first, a full backup (of all files) is taken. After that, any number of incremental backups can be taken.
• There are many different types of incremental backups, but they all attempt to only backup a small amount of data relative to the full backup.

Differential backup
• A differential backup copies files that have been created or changed since the last normal or incremental backup.
• Restoration requires the normal back up, plus the differential backups.
Continuous data protection
• Instead of scheduling periodic backups, the system immediately logs every change on the host system.
• RAID (Redundant Array of Inexpensive Disks) systems can be configured to do this.
• Others require special software to write to an external drive or save to a network storage device.

What about Backup Programs?
• Most backup programs compress everything into a single file which may be copied across multiple CDs or DVDs.
• Some times you can not recover the files because something has changed (i.e. new hard drive, new computer etc.)
• Often you cannot recover individual files or it is difficult to find the individual files because of the compression and the single file storage.

This Too Complex
• Look at what you have on the computer. Things can be divided into 3 main groups
• Programs etc. that were installed from a CD
• Programs that were downloaded from the Web
• Data, Pictures, Letters, Other documents or Videos
• Category 1 is already backed up if you have the disks (you may need updates.
• Category 2 needs the installation file backed up or an address to download a new copy
• Category 3 needs to be backed up
Next
• Determine the size of your hard drive(s)
• Go to the store and buy an external hard drive that can plug into a USB port and is larger than your hard drives
• Bring the hard drive home and plug it into your computer
• Create a file folder on the hard drive and change the name to identify that it is a backup and the date of the back up
And Then?
• Copy (Copy and Paste) those folders which need to be backed up into the folder that you have created. Try to capture the folders these files are in.
• At a minimum copy ‘My Documents’ to the external hard drive.
• Some programs save data in a structure of their own. Those should be backed up (copied) as well

Are There any Shortcomings?
• System files and programs are not backed up so that they can be restored.
• We are depending on original Disks for re-installation.
• Program files are not copied because for them to run under Windows they must be installed.
• If you wish to have this capability, one way is to create a mirror image in a folder so named and the software used to create this can restore the computer state to the one backed up.

TEPOA CUG
Comments are always welcome.
You are invited to show your favorite computer activity to either a lab group or at the monthly meeting.