Backups Backups are essential for recovering from - PowerPoint Presentation

Slide1

Backups

Backups are essential for recovering from

mistakes

deleting a file by accident

making changes to a document or file that turn out to be undesirable

disasters

house burns down

thief steals all computer equipment on premises

failures

hard drive fails

file becomes corrupted

filesystem

failsSlide2

Backup Considerations

Frequency of backup

how often you back up determines how much work you can lose

Number of backups

how many backup copies you have (at least one off site) determines how resilient you are to failures of backups themselves

Age of backups

it is not good enough to have 3 copies if they are all less than a week old!Slide3

Backups (cont'd)

Because of the disaster category, there is a wise saying,

"

if it's not off site, it's not backed up

"

A copy that is stored on the same device will disappear along with the original if the device or file system fails or is stolenSlide4

Automatic Backups

Example, Windows Backup

back up daily, weekly(default), or

monthly (frequency)

keep backups until you delete

them (aging)

Example,

Apple Time

Machine

backs up every

hour (good frequency)

retains the

following (good aging)

every hour for a day

every day for a week

every week thereafter

when backup drive is full, it removes oldest backups to make space for new backupsSlide5

Backup Retention

It is not good enough to keep just one backup, because you may not discover a problem until both the working copy and the backup copy have the problem

At least several backups of increasing age need to be retained

A file that's accidentally deleted in March and discovered to be missing in June could be restored from

February's

backupSlide6

Snapshot-style backups

Primarily to recover from mistakes or undesired

changes as you work

Make a copy of a file before you change it

Make a copy of a file while you are making changes

After you're happy with the changes and you feel the work is "stable", there is no need for the copy, which is often on the same driveSlide7

Snapshot-style backups (cont'd)

Different ways to preserve a snapshot of your work:

Copy the file with Windows Explorer

Copy the file with the command line copy command

Use your application's "Save as" feature, but remember this usually means you're now working on the newly named copySlide8

Ad Hoc backups

For large datasets (

eg

10TB)

store a copy (set of hard drives?) in a secure off-site location

keep a copy or two on site

keep track of the incremental changes

every once in a while (weekly, monthly, or yearly, for example) apply the incremental changes to a local copy, and trade that with the off site copySlide9

Windows Backup

Windows backup will wait for the next backup if the computer is asleep

Possible solution In

W

indows 7:

go to control panel\power

options

edit

plan settings

click

the link "change advanced power settings

"

In

the tree expand "sleep

"

"

allow wake timers" option.Slide10

Backup Management

You must be organized with your backup system

All (external) backup devices need to be labeled with the date and contents so they may be properly rotated (it's not feasible to keep every backup forever)Slide11

Backup Security

Anyone who has access to the backup devices (hard drives, tapes, DVD's,

etc

) also has access to all the most sensitive data on them

Encrypting the backups can alleviate this problem, but this adds a new dimension of managing encryption keys,

which is non-trivial in itself

Backups need to be stored physically secure and/or encrypted