Understanding Backup Hard Drives Made Easy (size, speed and interface)

by | May 22, 2012 | Business Continuity

Everything you need to know about understanding backup hard drives

Let’s face the facts. If you’re a computer user, (and if you’re reading this, I’m going to assume that you are), there will come a time when you have to replace a hard drive. More than likely, if you’re on this blog, you’re considering hard drives for Backup and Disaster Recovery purposes. Whatever the reason may be, you need a good understanding backup hard drives. The most important things to understand with hard drives are drive size, drive speed and interface.


Since its initial inception by IBM in 1956, hard disk drives have increased in capacity and speeds while cost and physical size of the device has decreased, (see Moore’s Law). It is important when choosing a back up hard drive to take into account the current data usage and statistics, such as the amount of data saved, as well as future projections of data change. A good practice to size a device based on two times the size of the server being backed up. That is to say, if you currently have 450 Gigabytes(GB) of data on a 500GB drive and you project that your company will pass the 1 Terabyte (TB) mark in 6 months, utilizing a 2 TB drive (or 2 x 1 TB drives) may be more beneficial than a 1 TB drive. Doing so minimizes the chance that your device will run out of hard drive space, and thus fail to back up critical information.


Another factor in choosing a drive is the data transfer rate and drive speed. The data transfer rate is how fast data is transferred from one location to another. In this case, data transfer rate specifically refers to the storing and retrieving of digital information from the drive itself. A typical desktop hard drive rotates at 7200 RPM with a data transfer rate of 1,030 Megabits per second. Data transfer rate and drive speed are particularly important when it comes to migrating data in servers and reducing the time it takes to perform a backup. At Datto, we use drives with no less than 7200 rpm and 64mb cache which we have determined, through years of testing experience, is the best and most cost-effective way of storing mass amounts of data.

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Most modern computers have SATA, SCSI, or SAS interfaces. It is important to note the type of interface, and how it can potentially influence the overall performance of the device. Our backup units currently use SATA interfaces as we have found them to 1) have a high compatibility rate with other hardware assets, 2) are very reliable and much more cost effective than alternative interfaces, and 3) easier to physically work with, improving the longevity of individual devices. While the SAS interface is the newest and has the most features, the high cost associated with those back up drives and their limited availability makes SATA the best solution for high-density, low cost-per-gig storage.

No matter the end use of the drive, it is always a good idea to understand exactly what is going into the final device. In the case of hard disk drives, all are not created equal. By understanding what differentiates each drive, you can better understand what your device is capable of, and what to expect from it.

Dale Shulmistra is a Business Continuity Specialist at Invenio IT, responsible for shaping the company’s technology initiatives -- selecting, designing, implementing & supporting business continuity solutions to bolster client operational efficiencies and eliminate downtime.