Aug. 1, 2002
There has been abundant discussion about glamorous technologies like imaging and digital X-rays that generate digital data in a dental practice. However, there has not been much talk about the seemingly mundane topics of data backup and disaster recovery. I have heard casual remarks like, "… I copy everything to a Zip disk," or "I burn it to a CD." k

by Ekram Kahn

Backup technologies and strategies for protecting dental office data

There has been abundant discussion about glamorous technologies like imaging and digital X-rays that generate digital data in a dental practice. However, there has not been much talk about the seemingly mundane topics of data backup and disaster recovery. I have heard casual remarks like, "… I copy everything to a Zip disk," or "I burn it to a CD." Although either of these two options is better than no backup at all, neither is a comprehensive solution that guarantees complete system restoration in the event of a catastrophic system failure.

There are as many strategies for backup and disaster recovery as there are colors in the rainbow. The most practical technologies for dental offices are redundant hard disks, tape drives, bootable recovery disks, disk imaging, and online backup. All of these strategies are most effective when mated with a documented disaster-recovery plan. The plan serves as a road map to guide you through the process of completely restoring your systems to working order, regardless of the type of failure. In this article, I will review the available backup technologies and give you guidelines to help you formulate a disaster-recovery plan.


When you hear that hard drives are "mirrored," it means that the system is configured as a RAID Level 1 system. RAID is an acronym for Redundant Array of Independent Disks; there are Levels 1 to 6. The numbering system for the levels of RAID merely indicate different configuration types, rather than implying that any one is better than the other.

For the typical dental office network, RAID Levels 1 and 5 are the most practical. RAID 1 involves disk-mirroring, where the master disk is simultaneously backed up by a slave disk. The slave disk is an exact copy of the master and, in the event of a master disk failure, can serve as the master disk until the failed disk can be replaced. For a higher level of protection, I recommend configuring servers with RAID 1 and an online spare disk drive. Then, if there is a failure of any mirrored disk, the online spare drive will act as the mirror. RAID 5 is an option I usually recommend on servers that are part of a large network (30 or more workstations) or a Wide Area Network servicing a multisite practice. RAID 5 systems are slightly faster performers but are more expensive and, in some cases, require more expertise to restore in the event of a failure.

With disk-mirroring, you protect against data loss as a result of disk failure, but you can't protect against software or database corruption because bad data simply will be copied onto the second drive. This problem can be circumvented by using a removable tape-backup system with a high storage capacity.

Tape backup technologies

Selecting a tape-backup system is difficult because of the variety of choices. The predominant tape technologies are TRAVAN, DAT, and DLT. TRAVAN tapes are more common because they are an affordable, consumer-grade technology that is used to back up home or small office computers. Reliability issues and relatively low storage capacities for TRAVAN tape systems are the reasons why I don't recommend this technology for protecting critical data like patient records. DAT (Digital Audio Tape) is a better choice for this purpose, because it typically is more reliable and can store up to 40GB of data. The best choice, though, is DLT (Digital Linear Tape) technology. It is the fastest, most reliable of the three options and has capacities up to 80GB.

DLT tapes are extremely durable and have been a stable technology platform for many years. That means DLT products will be available for as long as you intend to use the technology. Financial institutions have relied on this technology, and I believe it is the best platform for protecting the vast amounts of data that accumulate in digital dental practices. At a cost of $1,300 per drive - and $80 to $100 per tape - the price of DLT technology is a common barrier to entry. But consider this: What would be the total cost of losing your data? The servers that we currently provide to our clients all have DLT drives in addition to disk-mirroring. This combination has proven to be effective.

Online backup services

As broadband access to the Internet has become more prevalent, the concept of subscribing to an online backup service is technologically viable for the typical dental office. Corporations have used such services to recover quickly from catastrophic incidents like the World Trade Center bombing. These companies have information-technology budgets far greater than that of a dental office, as well as fully trained staff to manage all of the processes. However, with high-speed connections like DSL and cable modem lines, the option for a dental office to use an online backup service is limited only by the allocated budget.

Dentists are using technologies that generate significant amounts of digital imaging data. The storage requirements for imaging data grow at a much greater rate than for practice-management data, so transferring large amounts of data across a DSL or cable connection will have certain limitations. The bandwidth available with DSL lines varies and, at maximum capacity, can provide 1.5Mbs. That translates to 675MB per hour. If you assume that there are 16 hours between the time you close your office to the time you reopen the next morning, you can expect to back up as much as 10.8GB of data overnight. Obviously, this is dependent on the consistency of your connection. Some cable connections yield up to three times the bandwidth I used in my calculations, but you can safely assume that between 6 and 12GB of data can be transferred off-site during an overnight backup.

Assuming that you have the necessary broadband connection, online backup services may not be a cost-effective choice for your office. The typical service charges are based on the amount of storage you will require for your backup. The cost per gigabyte ranges between $35 and $50 per month. So, for a 10GB database, you would be looking at an annual cost of $3,500 to $5,000. Most corporations justify this cost by considering that they eliminate an in-house employee who would have been responsible for managing the backup process. Most dental offices don't have a dedicated employee for this task.

Let's examine the true cost of in-house tape backups, compared to an off-site online service. The DLT tape-backup system typically lasts five years before the drive must be replaced. So, consider $250 per year as the eventual replacement cost of the drive. You will need one tape for every day (5), week (4), and month (1) that your office is open - a total of 10 tapes - for a complete backup cycle that will have data available up to one month prior to a total data-loss event. Replace these tapes annually for a total yearly tape cost of $1,000. Add the cost of a staff member spending one hour per week swapping backup tapes and maintaining the backup system ($15 per hour x 40 hours per year = $600 per year). You now have a total annual cost of $1,850 for doing in-house backups. This cost covers up to 80GB of data storage capacity. However, the same storage capacity for an online backup service would cost $38,400 annually. Some may argue that dental offices don't have such high storage requirements, but I have a client who is using digital imaging and X-ray technologies in his office, and with a patient base of 3,800, he is adding 10GB per year. The average digital dental practice will acquire between 8 and 15GB of data each year.

Disk imaging and recovery CD

Disk imaging is a process where an exact copy of your hard drive, including all customized settings and files, is created for the purpose of completely restoring your system to a known good configuration. A disk image should be created for all of the workstations on your network. Typically, network workstations are not part of the nightly backup scenario for a dental office network. Therefore, to restore from a system failure, you would have to start from scratch and reinstall the operating system and every software program that was on the machine prior to the failure. This process would take several hours and might not achieve the desired level of restoration. If you created a disk image, though, all you would have to do is boot up the system with the emergency disk and follow a few steps to completely restore your system from the disk image in a matter of minutes.

Once you have created the image file, restoring is easy and fast. You can restore the saved image to the same hard disk or to a different computer. One caveat: If you restore an image (other than data files) to a machine that has significantly different hardware than the machine where the image was created, you might encounter problems. For example, the machine to which you restore the image may be unstable or unbootable. You can circumvent these issues to some extent by making sure that the machine you use to create the image on has all the drivers you may need on the machines to which you will restore that image. Your imaging solution should allow you to start the imaging program from either a floppy disk or a CD. Then, you can restore the image from the location you used to store it earlier. If, for example, your computer crashes and you can no longer start the operating system, you can boot from the CD that you created during the imaging process. When you restore an image file, your system is returned to the state it was in when you created the image.

Disk imaging is better than direct disk-to-disk copying, because an image file is compressed (requiring less storage space) and can be encrypted for security. I have used PowerQuest®Drive Image® 2002 with great success. This software application can be used to create complete recovery CDs that are bootable.

Rewriteable DVD/CD

People often insist that copying data onto removable media is the easiest method of doing backups. I agree that it is the easiest, but is it the most effective? There are several fundamental problems with this concept. Unless you have a practice that uses just a practice-management software program and you have no image data, the storage capacities of removable media - ranging from a paltry 256MB to a max of 4.7GB - will not be sufficient to completely back up all of your data. By having multiple disks to manage, it becomes a maintenance nightmare. When it comes time to restore, you will be running around pulling out your hair and screaming, "Where is Disk No. 3 from Backup Set 1 done on 11/21/…?!!!" Hard disks are cheap and getting cheaper, while DLT tape systems are the best choice for an off-site option. Therefore, for best results, keep everything on the server or on one tape, rather than spanning your data across several pieces of rewriteable media.


  • Imaging creates a compressed backup of your entire hard drive onto removable media such as CD-R/W.
  • When disaster strikes and you lose data ...
  • You simply pop in the CD and copy the image file back onto the hard drive.
  • Restoring your computer (and your valuable data) to its last saved, working state.

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