In the early 1990's the choice of backup
system for most computer users was fairly simple. Entry level - you're writing
your business plan or novel* - these could be safely backed up
floppy disks. In the
case of the small company or workgroup a
tape drive could be used
to save and restore critical data and applications, while bigger organizations
used tape libraries.
Today, a number of storage and communications technologies have converged
into the backup applications area. The result is that data users have a wider
choice of backup options than ever before. Many large data owners will remain
dependent on tape because of its low cost / megabyte. However, most small to
medium sized organizations would do better to look at other technologies for
their backup as replacements for tape, or to provide different survivability and
restoration characteristics. There are many factors which have to be weighed
into these decisions.
- the cost of losing data - see
the Cost of Owning and
Storing Data - by Overland Data
- the cost of installing and running the backup system
- the convenience of using the backup systems
- the time it takes to restore to a fully working system after a data loss
- the survivability of the system depending on environmental factors and
common mode failures
- personal preferences based on your previous experience with backup
technologies, or the need to retain compability with other sites (possibly
including your customers)
- the alternative cost benefits of taking liitle or no action at all
Most people don't think seriously about data backup until they have
experienced a problem.
However, many people also make the mistake of planning to cope very well
with a small range of possible data loss problems, while not planning at all for
many problems which could have a more detrimental impact on the survivability of
their organization. Here are some cautionary notes:-
- Problems with tape backup. How many tape backups do you use, and
where are they located?
I had a situation once, where I had to
restore some data from tape. The first backup tape broke. OK, I had another
copy. Then the 2nd tape broke. Mild panic set in, but luckily I stopped
and called a service engineer. The problem turned out to be a faulty LED in
the tape drive, which meant it didn't stop winding at the end of the tape. This
fault would have broken my last tape if I had been unwise enough to put it
in the drive. However, many modern tape cartridges are built more robustly. Refer
to the articles linked from our
tape drives & systems
- Problems with physical security. This affects all kinds of backup
including tape, RAID and any other system where the data is located on one site.
Many people think of fire or flood as being the main risk, but the risk from
crime is much greater. We know one web business which was adverseley affected
when someone stole their servers and all the backup systems and media. That's
also a good argument for using a
If your servers are screwed firmly into lockable cabinets, chances are
they'll still be there long after yoru desktop PC's have disappeared into a
waiting truck. It's also a good case for a redundant
You can load up a portable server as a mirror to your main server for your "must
keep alive" applications. If you discover one morning that your main
server has been stolen, the portable can help get your business restarted. Make
sure your portable is kept off-site at night, and synchronised daily.
- Problems with ageing/obsolete equipment. This affected me once when
I had a perfectly good backup tape system which had been running for a couple of
years. Then I upgraded to a new faster computer - with a 4 year jump in the
operating system. The old tape drive was supposedly supported on the new
version of the operating system. It never worked because of various clashes.
Fortunately this wasn't the disaster it should have been, because the old system
was still working, so I was able to upload all the old data onto the new system
using a networking connection. But if the old system had broken, I would have
discovered this problem too late... Sometimes, old media can be read in new
drives, but maybe the old backup software won't run on your new system. That's a
strong argument for storing your data in a way which involves the least amount
of software reprocessing, so that maybe some time in the future when the
installation media are lost or stolen, you have some chance or reading the data
back using a different package.
- Operator error. When you're restoring data from read/write medium,
and you make a mistake, you can easily end up deleting data which you did not
mean to on your backed up medium. Actually, it's easy to accidentally delete
stuff at any time... That's when a mirror drive comes in useful. One which
you only update once a day, instead of instantaneously. A RAID system
protects you from hardware failure, but not from operator error.
Some of the new backup technologies which are now available include:-
- Backing up a redundant fully workable alternative machine. This
route provides the fastest way of getting your system up and running again. At
the high end, some organizations will choose fault tolerant servers from
companies such as Sun
Microsystems or Resilience
Corporation. At the low end, even a small company can afford to have a
complete ready to run PC backup system which you can update throughout the
- Backing up to redundant disks. A RAID system can protect your data
from disk failure, but RAID systems can also have enough storage capacity to act
as a convenient fast access backup. Once a day you can backup up all your data
onto an external RAID, and know that if you need to restore something, it's
already in a form which you can immediately use. On a smaller scale, copying to
your Jaz drive and other removable
disk drives provides the same functionality at lower entry cost.
- Backing up to an off-site
location via the Internet. Large organizations have been doing this for
years using WAN technologies. Today, SOHO sites and medium size companies can
use products from
FreeDiskSpace.com, and others to
achive this. If you are worried about some other company having your data, you
can use the ftp data exchange in
LapLink.com's products to backup to your
own remote office office (or home).
- Backup up to a writable CD-ROM. One of my friends runs a network
training business. The more you know about technology, the more you worry about
what can go wrong. His disaster recovery scheme (which runs in parallel with
tape backup) is to record all his data once a week onto CD-ROM's. The argument
runs that you can buy a new PC anywhere with an integral CD-ROM. So if your
first backup system fails, then you go and buy a new machine with a CD-ROM drive
which can immediately read your data. The tape backup is necessary for those
less catastrophic situations when you need the data which was created in between
times. Assuming a weekly burn of CD-ROM's.
When lighning strikes...
OK in the real-world, you know that sometimes things go wrong. The plans you
made didn't prove to be as foolproof as you expected. So what can you do if
you've had a disaster with your tape or your disk. It's stopped working due to a
simple hardware failure, or been in a flood (or pseudo flood caused by hot Java
of the liquid kind) or the drive has been accidentally erased, or dropped, or
even struck by lightning... You really do need to get some critical data off it
- because the alternative is a lot of keying in data, or losing your newest
customer, or losing your job, or even your whole business.
That's where the data
recovery services come in. This remarkable industry has at its disposal a
wide range of technologies which can include removing the media from your disk
or tape drive, reconstructing the data, and even giving it back to you in a plug
compatible replacement which will actually fit back into your original system
if that's what you want. They can also provide tools and advice to help you
recover from the "operator induced errors" I mentioned above.
Other uses of backup devices
Massive floppy disks, such as the 250M byte ZIP drive have long been used by
graphics design agencies as a way of sending data for brochures to printers.
That's because 200M bytes still takes a long time to send, even using ISDN.
Another use that occurred recently in our own office, is when one of my
colleagues recently put together a PowerPoint presentation which included a
number of video clips. I think that once
marketing people begin to master
the audio visual potential in the latest version of PowerPoint, we could start
to see a sudden rise in the take up of this kind of backup media.
|Backup really is important
story:- One writer I know started his opus on a CP/M PC (a pre MS-DOS operating
system) and 5.25" disks using a really obscure word processor. The
writing took many years. Recently the original machine stopped working and
he had the problem of transferring all this stuff to 3.5" disks. That's
when the important backup became the printout which was scanned back in to the
new PC replacement.
||Backup really is important|
|"63% said they
encountered unreadable tapes when they tried to retrieve data with 76% of those
cases reporting a direct impact to their business from loss of productivity to
punishments for regulatory compliance infractions." |
|Tape Backup Fails Most Enterprise
from storage news - September 2005
Self-Encrypting SSDs (if you think you might need a future data recovery)..."
|SSD data recovery news
- August 2013|