Backup Technologies Proliferate

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 onto 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 page.

• 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 rackmount server. 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 portable server. 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.

• Problems caused by complexity. - In a very large system, which may include other storage technologies such as clustering, specialised software may be necessary to make sure that the individual mechanisms work in concert. See for example white paper from Architek - Felis Server - High Availability Cluster Server Solution .

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 working day

• 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	*True 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