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Data Tape types and sizes (Quick Guide)
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Data Backup and Archival
Do I need to backup data?
Only you can answer this question. The short answer says what value do you place on your data stored on Computers or Servers. If you lost your data tomorrow how would it affect you? A not well-known fact is that all Hard Drives will eventually fail; so to say that your systems are new and it isn't a large risk is giving yourself a false sense of security. Through our recovery services arm we have seen countless home users and businesses not have or not have an effective backup strategy and then suffer a hard drive failure. I can guarantee you will only let this happen to you once before
What type of occurrences do I need to need to protect myself from?
Data Protection is more than keeping your server room locked….
Allnetworks Australia is committed to providing up to date and relevant information to its customers new and existing. We hope you find the below information of use. If you would like and further information added, or have specific requests feel free to call or email us.
If you currently don’t back up your data and don’t want to start
I suggest you don’t read any further. (It may be bad for blood pressure!!
. Is your data really protected?
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Common Backup
terminology and types
Backup
Type
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Description |
Normal
backup
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It backs up all files regardless of the last time they were modified. It will usually also clear the archive bit on the file attributes |
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Copy Backup |
It backs up all files regardless of the last time they were modified, but does not clear the archive bit. |
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Incremental
backup |
Backs
up only those files that were created or modified after the last backup.
These backups look for the archive bit that is set ever time you modify
and save a file |
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Differential
backup |
Similar
as incremental backup, but does not marks the files as backed up. (Does not clear the archive bit) |
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Daily backup |
Backs
up only those files which were created today |
One tape rotation. – This involves using the same media every day for backup. This is the cheapest method and also the most risky. In the event of needing to recover data from more than 25hours before the last backup is impossible. It is only slightly better than having no backup
Five or seven tape rotation (one tape or media for each day of the week. The simplest tape rotation scheme is to have one tape for each day of the working week. Tapes are labelled: Monday, Tuesday, Wednesday, Thursday, and Friday.
Grandfather/Father/ Son is
the most commonly used backup rotation used worldwide today. Originally designed
for tape back up, it works well for any hierarchical backup strategy. The basic
method is to define three sets of backups, such as daily, weekly and monthly.
Simple additions to this methods is to have the most recent backups removed
from the site for safe keeping, allowing data recovery in the event of a disaster.
· Daily - on the "son tapes"
· Weekly - on the "father tapes"
· Mmonthly - on the "grandfather tapes"
This strategy provides you with the ability to restore data from the last week, plus any Monday over the last month, plus any month for as many monthly tapes as you have. Variations on this scheme are available, and provide a trade-off between the number of tapes required, and the number of monthly tapes available. Most commonly 50 tapes are used in the rotation
The Tower of Hanoi a
complex strategy where five tapes are used - called A, B, C, D, E.
A is used every other
day
B is used every 4th
day
C is used every 8th
day
D and E are used
every 16th day, alternating
This ensures that
data is available from the last day, 2 days ago, and three other times in
history. However, the range of history of backup is dependent on where one is in
the cycle