Drobo (3rd gen) to Drobo 5C, introduction

My long history with external hard drives was covered in an earlier article, so I will just summarize:

I’ve gone through a bunch of hard drives and external enclosures since 1999.

Last year I shared a multi-part series about migrating from a 2nd generation Drobo to the newer 3rd generation models. The 3rd generation version solved most of the performance issues, especially when it came to the time it took to rebuild after replacing a drive. It also added a very important capability: Dual Disk Redundancy

See: What is Dual Disk Redundancy?

This is very important because, without it, when (not if!) a drive fails, during the time it takes to rebuild on to a new drive, any other drive failure will cause loss of data. With drives becoming larger and larger (I upgraded mine, rebuild time also increases. If you buy multiple drives at the same time, you increase the likelihood of getting multiple units that have the same flaw from a bad production run, which increases the odds of a multi-drive failure.

It may seem unlikely, but from reading many articles about RAID systems over the years, it’s far more common that I would have thought.

I have worked around this over the years by always having multiple drives and backing up my important data between them. Thus, on my two Drobos, I have my most important data copied to each unit. This way, even if a Drobo completely died on me, I still have my data on the other one. (It’s also good to have backup hardware in case of a failure. I can swap my drives to the still-working unit and get to anything I need while I wait for the failed unit to be repaired/replaced.)

Of course, this doubles the hardware cost…

With Dual Disk Redundancy, you can set up a Drobo to protect data in a much better way. Normally, every bit of data exists on two drives/ if one drive fails, there is always a another copy. With Dual Disk Redundancy, the data will exist on three drives, so if two fail, you still have a copy.

The problem is … you lose storage space. A 4-bay Drobo filled with four 3 TB drives gives you 8.17 TB of storage for data. If you enable Dual Disk Redundancy, it drops to only having 5.44 TB available. You can see this at the Drobo Capacity Calculator:


When the 3rd generation Drobo came out, they added Dual Disk Redundancy support, but if you were migrating from an earlier 4-bay unit, you could not make use of it unless you had enough free space available.

At some point, Drobo also started making 5-bay units,. This allowed you to have as much storage as a 4-bay offered WITH Dual Disk Redundancy enabled.

The problem is, those 5-bay units were expensive! A 3rd generation 4-bay Drobo sold for $299 or so, while a 5-bay direct-attached drive was $699! That’s quite the premium just to get one extra drive bay.

This changed last October when Drobo announced the new Drobo 5C.


At $349, it’s a much better value. It ONLY has a USB-C port, and comes with a cable to plug that in to a USB 2.0/3.0 port on your PC/Mac, so if you preferred Thunderbolt, SATA or FireWire, you are out of luck.

I will soon be receiving a unit to review, and will begin a multi-part article about migrating from a 4-bay Drobo to the new 5-bay 5C model.

More to come…


4 thoughts on “Drobo (3rd gen) to Drobo 5C, introduction

  1. Pingback: Drobo (3rd gen) to Drobo 5C, part 1 | Appleause

  2. Pingback: Drobo (3rd gen) to Drobo 5C review | Sub-Etha Software

  3. Pingback: Drobo (3rd gen) to Drobo 5C, part 2 | Appleause

  4. Pingback: Drobo (3rd gen) to Drobo 5C, part 3 | Appleause

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