Backup
What would you
do if you turned on your computer some morning and you got
the message "System disk unreadable, unable to boot",
or worse yet, there is an empty place where your computer
used to be? One of the first questions you will be asked is
"Do you have a backup?" The intent of this guide
is not only to give you some options on how to back up your
system, but to help you put together a Disaster Recovery plan
in case you need to actually use those backups. Your recovery
plan can be as simple as having a boot disk and the software
needed to read your backup tapes, or you may have to consider
hardware replacement and setting up shop at a remote facility.
Our Simple Share ™ system has proved to be very valuable to companies looking to back up and restore data easily.
Why Backup?
When you consider
the years worth of data contained in your computer and the
value of its software, the files on your hard disk may be
worth many times the cost of the computer itself. You should
be able to recover from a total loss of your system due to
a disk crash, computer theft, fire or other disasters. However,
one corrupted or mistakenly deleted file can be just as bad.
How long would it take you to rebuild that database or contact
list? Could your company or department continue operations
without it? Whether you are responsible for all of the computers
on your office network, or just your individual system, you
should have a backup and recovery plan.
How to Back up
One of the first
decisions that needs to be made is who should be responsible
for doing the backups. If you only have one system, or you
want each person to be responsible for backing up their own
system, each computer should have its own backup device. If
you have a number of systems, a portable backup device can
be taken from system to system. You can also have your systems
backed up automatically if they are connected to a fast network.
The
easiest method of backup is to have a duplicate hard drive
in your system. Data can be copied to the second drive as
often as needed. The danger in this method is that if your
entire system is damaged or stolen, your backup is also lost.
The
most popular backup method is tape. It is an inexpensive medium,
and has enough capacity to back up most hard drives. The problem
with tapes is that they are easily damaged. You should periodically
check that you can restore from your tapes and replace them
with new ones frequently. You should also clean and inspect
your tape drive regularly. Tapes have a short storage life
and are not good for archival backups.
 You
can combine the ease of backing up to another hard drive with
the portability of tape by using a removable media disk drive
such as the Iomega Zip (100 Mb) or Jazz (1 Gb) drives. These
disks are more dependable than tape and you can locate and
restore individual files more easily. The downside is that
these are more expensive than tape, and in the case of Zip
disks, the storage capacity is low.
A
newer method is data warehousing. Your data is backed up via
modem or the Internet, and stored on your service providers
systems. This can be setup to be done automatically and also
takes care of the requirement to have an offsite copy of your
backups. The downside is that large amounts of data can take
a long time to transfer using a modem.
 If
you need archival storage of data you should consider recordable
CD-ROM or Optical disks. These are less likely to be damaged
and have a longer storage life. The drive and media costs
are more expensive for this format.
When
deciding on a format, you should look at the cost per byte
of storage and the amount of data you will be backing up.
While it is important that the backups are reliable and meet
your storage needs, the media costs should not prevent you
from making frequent backups.
What to Back Up and How Often
What
you back up and how frequently depends on how you value the
data. A directory of old memos might be OK to copy to a floppy
disk, every once in a while. A database or contact list that
changes frequently should be included in a daily backup. If
the loss of even one day's worth of data would be significant,
you may want to copy the file(s) to another disk several times
a day or set up disk mirroring.
A
good backup plan should include;
Daily incremental backups of files that have been added or
changed since the previous daily backup.
Weekly backups of all of your data directories.
Monthly backups of the entire contents of your hard drive,
including system files, preferences and programs.
Some
backup strategies exclude programs from the monthly full backups.
Before you decide to do this, consider the amount of time
it would take to restore your system from the original distribution
disks and their availability.
You
should keep a rotation of two or three cycles (daily, weekly
and monthly) of your backups. Do not leave the backup media
in the drive; if the system is stolen, your backup will be
gone as well. It is EXTREMELY important that you keep one
set offsite. If your office is destroyed or inaccessible,
you will need to use this set to restore your data. Your application
disks should be kept offsite as well if they are included
in your recovery plan.
Media Rotation Schedules
Grandfather-Father-Son
The most commonly used media rotation schedule is "Grandfather-Father-Son." This scheme uses daily (Son), weekly (Father), and monthly
(Grandfather) backup sets.
 The GFS scheme begins with the daily backups. Typically, four
backup media are labeled for the day of the week each backs
up; for example, Monday through Thursday. Each tape is recalled
for use on its labeled day. If only a one-week version
history of files is maintained, then each tape is overwritten
each week. In order to maintain a 3-week version history of
files (recommended), more tapes are required. For example
this week's Monday tape will not be overwritten for 3 weeks.
Weekly backups follow a similar scenario. A set of up to five
weekly backup media is labeled "Week1", "Week
2", and so on. Full backups are recorded weekly,
on the day that a "Son" media is not used.
Following the example above these would be "Friday"
tapes. This "Father" media is re-used monthly. Five
weekly tapes are required in order to maintain a one-month
history of files, as some months have 5 weeks.
The
final set of three media is labeled "Month1", "Month2",
and so on, according to which month of the quarter they will
be used. This "Grandfather" media records full backups
on the last business day of each month. If your backup plan
follows a corporate fiscal calendar, then your monthly tape
will take the place of the week 4 or week 5 weekly/Father
tape, depending on the month. If your backup schedule follows
calendar months, then your monthly backup will vary throughout
the year, replacing a daily or weekly tape. Typically, monthly
tapes are overwritten quarterly or yearly (recommended), depending
on version history requirements.
Each
of these "media" may be a single tape or a set of
tapes, depending on the amount of data to back up and the
type of backup used (incremental vs. full). Weekly and/or
monthly tapes are generally pulled as archive tapes.
Online
Services - with recent developments in broadband connectivity it
is now viable to back up to a central server via the Internet.
There are a number of reasonably priced services available and well worth investigation.
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