Security and Backup
• Avoid disasters – have a
good backup policy
• Avoid disasters – have a
tight security scheme in
place
• UK law dictates the
board of directors are
responsible for security
issues – the safeguarding
of the data (not the IT
department /security
officer)
Backup
• Various options here. The
aim is to ensure you can
recover from a disaster
such as a hard disk
failure. If the hard disk
fails, it will be
impossible to retrieve
data from it. Copies
MUST be taken
regularly… just in case.
Security and Backup
Backup key points:
• Decide with what, when,
how and what is to be
backed up:
• WITH WHAT: floppy disk,
tape streamer such as a
Travan or DAT device ..
or a larger capacity DLT
drive? It comes down to
capacity/speed/cost – look
through recent magazine
reviews/adverts for details
• WHEN: as often as needed
(within reason) as the
data/files change often
• Exact times will depend on
the volume of data
involved
• Daily tapes + weekly tapes
allows back-tracking
through a week or month
• During office hours or
after?
See WHATIS.COM
Security and Backup
HOW:
Full Backup
• A full backup is simply that: a complete backup of every single file.
• The advantage of such a backup is that files are easily found when
needed. Since full backups include all data on the hard drive, you do
not have to search through several tapes to find the files you need to
restore. In case you need to restore the entire system, all of the most
current information can be found on the last backup tape.
• The disadvantage is that doing nothing but full backups leads to
redundancy which wastes both media and time. A backup strategy
would normally include a combination of full, incremental and/or
differential backups.
See: Backup (Internet link)
Another includes RAID (Internet link)
And another with Grandfather/father/son (Internet link)
Security and Backup
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HOW:
Incremental Backup
Incremental backups include files that were created or changed since
the last backup (that is, the last full or incremental backup).
To achieve this, the status of each file must be recorded either within
the backup software or through the use of the archive attribute of the
files. If no previous backup was made, an incremental backup is
equivalent to a full backup.
Incremental backups make better use of media compared to full
backups. Only files that were created or changed since the last backup
are included, so less backup space is used and less time is required.
The disadvantage is that multiple tapes are needed to restore a set of
files. The files can be spread over all the tapes in use since the last full
backup. You may have to search several tapes to find the file you wish
to restore. The backup software can minimize this by remembering
where files are located; however a restoration may still require access
to all incremental backups.
Security and Backup
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HOW:
Differential Backup
A differential backup includes all files that were created or modified
since last full backup.
Note the difference between incremental and differential: incremental
b/up save files changed since the last (incremental or full) backup,
whereas differential b/up save files changed since the last full backup.
The advantages over full b/up: it is quicker and use less media. The
advantage over an incremental b/up: the restore process is more
efficient - at worst, the restore will require only the latest differential
b/up set and the latest full backup set, whereas an incremental b/up
could require all incremental b/up sets and the full b/up set.
The disadvantage of a differential backup is that longer and longer
time is needed to perform them. The amount of data backed up each
time following the full backup gets larger and larger. Compared to
incremental backups, differential backups are more wasteful of time
and media - each backup would store much of the same information
plus the latest information added or created since the last full backup.
Security and Backup
WHAT: you pick what
files should be
included depending on
how “valuable” they
are
• All systems need a
complete backup –
software/OS/files
(Why?)
Security and Backup
To look for:
Other points:
• Grandfather-father-son
backups for batch
processing systems is
used
• See p281 / ch. 59 for
an example
• RAID
• Disk Mirroring
• And what about
Internet Backup
options? (See
whatis.com) and…
• http://www.ibackup.co
m/intro.htm
Security and Backup
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Security Issues
• Termination ! Out NOW &
Personnel policy to cover: escorted off the premises …
and User Name removed from
Recruitment – references
needed! Most damage to
the system immediately:
systems/files is done by
WHY?
employees…
• Employee code of conduct
Training – to stop errors
(IT01 – re-read ch.11 “Codes
Supervision
of Practice”)
Appraisal
• Passwords?
Separation of duties –
duplication of key jobs