Bob wrote
> Is the only answer a raid system or are there cheaper automatic
> alternatives?

Hi Bob, this is a very large "can o' worms" (IMHO), and the answer(s) could
be long and laborious.

Let's start on the premise that we are talking about our livelihood, and
therefore the storage of digital data files (I guess mainly photo's in this
context) is (a) important and (b) to be taken seriously.  

Data long term storage, archiving and retrieval is big business in the
corporate world and solutions can run into some very big sums.  Now before I
get "flamed" for talking about big money, it is still all about context -
some people need the best solution (almost) regardless of cost, and others
will be on a shoestring.  

RAID is not a long term solution for storing your work (data).  RAID may be
a useful part of your data management strategy, but it is not the only part.
On the subject of RAID (Redundant Array of Inexpensive Disks) - a lot of
times I see RAID used to provide faster access and larger volumes
(striping), in that type of RAID, if one disk in the array fails then all
data on all disks in the array is lost.  Mirroring is more elegant (if the
first disk fails then the mirror takes over, with all your data intact).
Whichever RAID solution is used (there are more) we are still talking about
hard disks in one computer that could be subject to one of many disasters.
Examples:

A virus  
Theft
Fire
User error
Malicious attack

In all above examples RAID will not help, it is concerned with physical
failure only.

What is needed is the ability to create a back-up copy of your data in a
format that will be reliable (long term), is not reliant upon a particular
host, and does not have to remain co-located with your primary
source/computer.
 
For the purposes of brevity (!) I will not write volumes on what possible
solutions exist (unless requested to do so), but there are some good
reasonable price options out there, mainly tape based, that have features
that a few years ago were only available to corporates with very deep
pockets.  E.g.  Capacity, speed, longevity, quality software to control and
span tapes, automatic archiving etc.  Cheaper alternatives are more labour
intensive (a DVD burner is my current favourite) - check the archives for
debate on longevity of CD-ROM media.....

BUT whatever physical back-up medium is chosen, the only way that this will
work is by creating a WORK-FLOW to actually do that back-up.  This may be a
culture shock for some, and (if you have a serious business or desire to
preserve your data) should be done on a more regular basis than you think -
once a day, automatically overnight is my standard recommendation.
Following that is the (in most cases) manual discipline of incremental tape
management (say 20 tapes - 1 per day) change the tape daily, every week,
take a tape off-site (to your mum's if you like) and every 20 days stash
your clearly labelled tape (off-site) and replace it with a fresh tape. This
type of system means you can always step back (recover) from the disaster
that you hope won't happen - but as you see on this list, and in the web
based news - happens to lots of people/business/computer systems all the
time.   Old adage - prevention better than cure.  Computers can be replaced
data (photo archive/library) cannot.

Sorry if this is a long post - tried to get some reasonable advice on what
is a big topic.  HTH.

Phil



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