Disaster Recovery

Testing Methodology

As Mediasonic does promote these units as an “instant storage solution for archive backups” and that “You will never need to worry about your hard disk drive malfunction with the Raid technology. The instant duplication of data gives you peace of mind in the event of hard disk drive failure. You ALWAYS have a back up” we here at HWC wanted to test this claim to its fullest. For each mode that the enclosures offered we started by first formatting the hard drives and then filling them to the maximum capacity offered at in a given mode. After this was completed and we then verified that the data was indeed stored on the external drives before simulating a catastrophic failure. This failure was accomplished by turning off the unit and removing one of the hard drives. We then turned the unit back on and checked to see if the data was still available.

Test Results

Single Mode

In Single mode the enclosure hard drives showed up as 2 separate drives. When one of the hard drives was removed the data on that hard drive was gone, but all data on the other hard drive was still available. This mode is therefore best suited for storing data that is either of little value or for short term use only. It is strongly recommended that any important data be properly backed up to a different medium and/or location. Single Mode is best for when either only one hard drive is available for use in the enclosure or where two separate hard drives are required for storage (e.g. two separate databases).


RAID 0 Spanning Mode

In Spanning mode the enclosures' hard drives showed as one large single drive. When one of the hard drives was removed all data appeared to be lost. However, when the “surviving” hard drive was reinstalled into a computer all data was available. This mode is therefore best suited for storing data that is either of little value or for short term use only. It is strongly recommended that any important data be properly backed up to a different medium and/or location. Spanning Mode is best for situations that require larger than normal amounts of data to be stored to one drive (e.g. one very large database).


RAID 0 Striping Mode

In Striping mode the enclosures hard drives showed as one large single drive. When one of the hard drives was removed all data was lost. Reinstalling the hard drive in a computer did not allow for retrieval of ANY data. All the data on the remaining hard drive was found to be corrupt. This mode is therefore best suited for storing data that is either of little value or for short term use only. It is strongly recommended that any important data be properly backed up to a different medium and/or location. Striping Mode is best for situations that require larger than normal amounts of data to be stored to one drive and where speed is more important than data reliability (e.g. one very large database with speed sensitive time constraints).


RAID 1

In RAID 1 the enclosures hard drives showed as one single drive. When one of the hard drives was removed all data was still secure. The only noticeable difference was that the HDD2 Failure light went on. By reinserting the now reformatted second drive the enclosure immediately started to rebuild its array. Rebuild time took a little over 5 hours to complete. This mode is therefore best suited for storing data that is important and is best suited for use as an external backup.


Before we continue I would like to mention the “Support” that is available online at Mediasonic.com. When things do go wrong customers usually like to be able to go to the manufacturer’s website for help. Unfortunately, this is not possible with Mediasonic. The “online support” amounts to one sentence listed under “Support” on each products individual page. “Please use Two Identical hard disk drive” is less than helpful and definitely does not engender good will to a company, especially if that company’s product just failed. While I would like to have seen a forum, even a short FAQ would have been better than one sentence in “Engrish”. That being said, there is a link on the Mediasonic site to Seagate's Data Recovery Services form which is a pay-per-use data recovery system in which Seagate evaluates your data loss before you ship you drive to any of three Canadian or 13 US recovery labs. You can find the form here: https://services.seagate.com/online_...F00639031945B4


Enclosure Replacement

It is quiet conceivable that the hard drives in the enclosure may actually outlast the array and we were interested to see if this would cause the data stored on the drives to become lost as well. By simply swapping the hard drive cage with the hard drives and backplane still attached and reinserting it in the other enclosure and we were able to quickly and easily verify that the data was still safe. It did not matter what mode the original enclosure was in, just as long as the second enclosure was in the same mode. This is very reassuring as any device can fail, but recovering from such a disaster is relatively easy.