CD Backups: Good or Bad?
I have heard you say on your radio show that you don't like CDs as a backup system. Why is that?
This question was answered on August 23, 2006. Much of the information contained herein may have changed since posting.CDs have had a dramatic impact on the computer world because of their enormous storage capabilities at a relatively low cost The problem with this great technology is that too many folks think it's an infallible technology that can be abused and last a lifetime.
While CDs are certainly more durable than traditional streaming tape, they are quite sensitive to many factors that can ultimately determine whether you will actually be able to read the data in the event that you need it.
I don't have a problem with folks that use CDs as a part of their data backup strategy; I just don't like it as the only 'safety net' for critical data.
We routinely see folks in our data recovery lab with a pile of CDs that they thought had their critical data stored, but for some reason they can't access the data on them
There are two distinct processes we need to cover; the first is a single burn 'archive' (CD-R) that is intended to be a long-term storage device (photos, videos, old financial records, etc.) and the second is the repeated use of the same disk (CD-RW) for regular data backups.
For single burn archives, it is critical that you use top quality name brand media that actually incorporates some solid technology to manufacture the disks (if you haven't heard of the company, don't buy it!) Elements such as cheap dyes, shoddy adhesives or little to no protective coatings over the recording layer can have a dramatic impact on whether you will be able to read the disk in future years.
If it's critical data, always make two copies Claims of 50 to 100 year life spans have been made, but there are a whole host of things that can reduce the actual life of the disks Unlike stamped commercial disks, computer burned disks are much more sensitive to light, heat and humidity.
Keep them out of direct sunlight, avoid wide temperature fluctuations and high humidity and remember to protect the label side of the CD The back side of the label is where the data is stored, so if the label gets scratched off, your data is gone!
Bending disks to remove them from their jewel cases can create tiny cracks in the protective layer which over time allows oxidation of the reflective material to occur (resulting in lost data).
If you store your disks horizontally over a long period of time, warping can occur depending upon what else is on top or below the disks, so always store them vertically in their jewel cases.
If you place an adhesive label on the disk that has corrosive glue, it can eat through the various layers, so make sure to use soft tip markers to label the disks.
When it comes to re-writeable media (CD-RW), the quality of the disks is even more important and cycling the media is critical Always use multiple disks and rotate them so you have some level of redundancy After 6 months of weekly use, replace with new media because re-writeable disks can suffer from media fatigue if overused.
Using CDs in combination with an external hard drive system backup or an off-site Internet-based backup system is a much better strategy, so that you are not betting on a single backup (A free 30-day trial of the Internet backup system we talked about on the radio is available at DataDoctors.com.)
By using multiple backup procedures, you can dramatically reduce the likelihood of ever needing expensive data recovery services If you want to see where the holes in your backup procedures are, review your disaster recovery plan in the event of media failure, fire, flood, theft and employee sabotage.
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Posted by Ken of Data Doctors on August 23, 2006