This topic is not directly related to networking, but I feel that I must mention this.
Please take the time to read this page completely , it contains important information, like
the Backup Media Sets and Backup methods.
Unless you installed a network just to be able to play network games, you use the network to
share data. Data is valuable and you always have to think:
"how much would it cost me to get the data back , in case it disappears from the system ? "
Very often, the value of the data on a system is much higher (maybe even millions of $) than
the value of the PC, so an effort must be made to protect this asset.
Think about backups like an insurance:
You need insurance (and pay for it), but hope that you never need it !
It is the same with backups: You make them , hoping that you never need them, but it is too
dangerous to live without them (there are reports about several companies, which had serious system
crashes where they lost all data and did NOT have a good back: they went out-of-business ! ).
Why do you have to make backups ?
What could cause the data on your system to get destroyed ?
Your harddisk stops working. Today, disks are fairly reliable compared to 20 years ago
(Example: the old HP 7920 removable 50 Mbyte disk drive needed to be recalibrated every 3 months, otherwise latest a month later the read/writing head would touch the disk-surface and distroy it phisically ! ), but it
Much more often data is accidentially deleted by the user/operator and you need a method to
get it back.
no yoke, it really happens : I have an example from a mini-computer system, where the system
manager was fired, the management made the mistake to let him go back to the system after
giving him the "bad news": he formated the disk and every s/w and backup tape !
While I am writting this page, there are huge floods in the northern part of Italy, the
river "Po" is 7 meters above usually level and is floooding cities.
Or you have a very heay storm with too much water on the roof, which caves in.
Or a water-pipe breaks and floods the computer room.
buildings burn down. It is very easy to get quickly replacement hardware, but where is then the data ?
Systems get stolen and it happens more often than you think.
This is today maybe the most important reason for backups: some viruese are very destructive
and delete some or all files from your disk.
This list should be sufficient to convince you to make backups.
What media should be used to make a backup ?
I have people say: "Oh, we have a RAID-5 disk-array to protect us against backups" or
"I make my backups to my second harddisk".
How much does this protect you against all reasons listed above ????????
Rule #1 for backups:
Backups must be made on a media, which can be taken out from the system and
must be stored in a SAFE location !
It does NOT help, if you make backups on tapes, but store them all next to the system, because a
fire would destroy them with the computer. In professional environments, backups are stored in
fire-proof safes or outside the building in bank-safes.
some other statements: "I make my backup's to floppy".
Todays modern PC's have 10+ GByte disks, it takes approx. 750 floppies to backup 1 GByte,
not to mention the time.
Rule #2 for backups:
The backup-media must be sufficient in size to allow the complete backup to be made without
having to swap the media, to allow an un-attended backup !
If you have to be present during the backup to swap cartridges or tapes every x minutes, experience
has shown, that you will stop very soon to make backups.
A question whch I asked some people with a tape backup device: "Show me your tapes".
They showed me the ONE ONLY tape, which came delivered with the backup unit, which they
had used every day to make their backup.
Now, what if you delete something and do NOT recognize that you still need it for a week ?
Then you will also have overwritten already several times the tape with the data with new backups
not having anymore this data !
Also, many backup media are not 100% reliable, especially tapes, so what happens if a backup media
gets a read error and it is your only backup media ? You have no moe backup !
Rule #3 for backups:
Backups must be made on several sets of backup media, allowing you to go back a
pre-defined time into the past to be able to recover data and to be protected against a
bad backup media.
I will not talk in detail about all different types of backup devices.
For home use and for small business usage , a typical backup device will be a tape-drive
(Floppy streamer or TRAVAN drive).
When more capacity and faster data-transfer is required, DDS - tapes (Digital Data Storage,
the computer equivalent of Audio DAT tapes) are often used.
In any case: tapes can NOT be used forever. Each time a tape is used, it is flexed by the winding
action, which will sooner or later damage the magnetic surface, where the information is stored.
Therefore, tapes need to be exchanged in regular intervals.
Backup stragegies and methods :
|Like all other erasable / reused backup media, tapes have to be used|
in Backup Media Sets to be able to recover data delete some time
ago in the past. You can use different backup methods to reduce backup time
Since this is a Networking website, I will not futher into details on actually running a backup
program. Once you understand the basics of Backup's, most backup programs work very
similar, like the Backup of Windows 98 SE: