Understanding External Backup devices

There are quite a few backup devices available and we get a lot of questions about which ones to use. A recent case which crossed our bench reminded us how important it is that you the user knows what some of the terms mean when you’re buying these devices.

In this recent case a customer submitted a device with the word RAID on the outside that had failed, he was a bit confused and thought the device had redundancy built in to protect his files because it said RAID. The fact is there are several kinds of RAID drives and the kind he had was a simple stripe set. Although it provides large size and good performance it is the worst for reliability as any failure on either drive will cause all data on both drives to be lost.

When buying a RAID device for your data be aware that:

RAID 0:

• Gives best performance for the dollar
• Gives best drive size for the dollar
• Has no redundancy
• Splits data between two physical drives
• Data will be lost and unusable if either drive fails
• Requires 2 or more drives
• Can be implemented with a hardware controller or through most operating systems built in drive management

RAID 1:

• Provides cheapest form of Real Time Backup
• Makes an exact copy of each byte of data from one drive to another
• Allows for quick recovery
• Requires 2 or more drives
• Can be implemented with a hardware controller or through most operating systems built in drive management

RAID 5:

• Provides best performance of redundant drives
• Uses algorithyms to store redundancy data across all drives for the array
• Allows data to survive any single drive failure and be rebuilt after the failed drive is replaced
• Requires 3 or more drives
• Requires a special controller or server software to manage the splitting of data

When buying an external backup device, most do not include RAID and should be used only as a backup, never trust a single form of storage. For RAID 0, these drives should only ever be used for short term storage and should not be relied on as a backup device due to their tendency to fail. RAID 1 or 5 should be used for redundant storage, if your data space and performance needs are minimal a RAID 1 NAS box or external device should suffice, if you deal with a great amount of data or require both large sized drives and redunancy then RAID 5 becomes the better choice despite the additional costs.

As always feel free to submit your questions and we will answer as many as we can between our FAQ and this blog.