Can a Drobo Replace WHS Drive Extender? Part 2

We left off on Part 1 with the Drobo fully loaded (4 x 80GB Hard Drives) and the results of a super unscientific transfer speed test for the Drobo.  If you have not caught up, here is the link for your review

Can a Drobo Replace WHS Drive Extender? Part 1

To restate the purpose with a question:  Could I use a Drobo device to replace the functionality that is going to be lost when Drive Extender (DE) is removed from the current Windows Home Server code named “Vail” build? Primarily, the file-based replication system that provides the following:

1. Multi-disk redundancy so that if any given disk fails, data is not lost
2. Data expansion by supporting any type of hard drive (Serial ATA, USB, FireWire etc.) in any mixture and capacity — similar in concept to JBOD
3. A single folder namespace (no drive letters)

So if DE is a form of RAID…

Just How Does A Drobo Do RAID?

Drobo uses a flavor of RAID they call BeyondRAID.  It is Drobo proprietary  technology and it protects from drive failure like traditional RAID, but provides the experience of a hard drive that does not break and does not get full.  Like drive extender, it allows users to mix any drives, add new drives to expand capacity, and replace smaller drives with bigger drives.  BeyondRaid explained at Drobo.com.

Mario from Drobo explained it this way…

Drobo uses a combination of striping and mirroring to make use of the available space across mixed drives, with parity distributed across the drives so you can pull any of them.  If there is one drive that has more capacity than the others, some of it will not be protectable on other drives, and will be reserved for expansion.  The online capacity calculators can show what space is use for protection, what is available to data, and what can be used when expanding to additional drives of higher capacity – http://www.drobo.com/resources/drobolator.php (note – we don’t have 3TB or 2.5 as options for the calculator, yet…)

BeyondRAID has a virtual hotspare concept and does proportional rebuild for only the real data and not empty space in the event of a drive pull / failure.  So, rebuilds can be much faster than traditional RAID, and in the review creation and formatting has been fast.  In the event of any failure, data is rebuilt using remaining capacity on existing drives, and when sufficient free space exists the system gets back to full protection ready to manage another failure without having touched the GUI.

Thanks Mario from Drobo for help with this section.

So What Does This Mean For You and Me?

What it amounts to is this.  If I have a 4 bay Drobo, and I put ONE drive it, approximately 50% of it becomes available for use but with no data protection.

Add the SECOND drive (and since the Drobo only worries about real data and not empty space, it formats very quickly (if your drive is not full).   The unit acts like a RAID 1 device, mirroring the data both drives.

Add the THIRD drive and the Drobo begins to provide data protection.

The FOUTH drive will add to the over all capacity.  The final result is 220GB of data storage for 320GB of drive space with that 220GB protected from drive failure.

So What Happens When a Drive Fails?

One of the main reasons I use a WHS is to protect again a single drive failure.  The most common causes of data loss, besides user error, is a mechanical drive failure.  So what happen in a Drobo when a drive fails?  I have made a short video.

I could have inserted a larger drive into Drobo during this test (which I will do later in the review) and it would have used that drive as part of the solution.   I did want to show what would happen if you didn’t have a drive available to add right back in and what that meant for your data.

It would be good to note here that during the recovery process, the data may not be protected if another drive failed or was removed from the pool.  The Drobo S model (coming in the future post) would allow up to 2 drives to fail at the same time.

One of the questions I got from the Home Server Show Forums was, could I read data from a drive that was pulled from the Drobo?  I didn’t show this in the video, but the answer is no.  Windows requires you to format the drive before it will allow you to access it.

Drive Temps?

Another question I received in the forums for this review was on drive temps.  I took this opportunity to check the drives during this process (since I knew they would all be working hard) and physically checked how warm they had become.  To my surprise, they were very cool.  There is a fan in the back of the until that provides good air flow across the drives.  (Double click on the picture of a closer look!)

So the Drobo is Full, Now What?

We started this review with 4 x 80GB hard drives and today I received some larger drives in the mail.  The operation is simple, fill up the Drobo by copying data to itself until it becomes full and then see how the Drobo responds.  We will once again shoot some video to show how it’s done.

When we started, the Drobo Dashboard looked like this…

Here is the video.

Current State?  Below is a shot of the Advanced Admin Console from the WHS.  You can see very little has changed since we have still not reached 2 TB of “Protected” or BeyondRAID Storage capacity.

A look at the Advanced Controls – Data tab on the Drobo.

The Drobo Dashboard showing available space.  Big difference from the one above before we began adding drives.

So what have I learned in Part 2?

Pros

1. It really could replace a good chunk of the functionality that today is handled by DE.  If I just look at the three functions of DE from the beginning of this post:
   1. Multi-disk redundancy so that if any given disk fails, data is not lost  – With the reviewed Drobo unit, I could lose one drive and my data would be safe.
   2. Data expansion by supporting any type of hard drive (Serial ATA, USB, FireWire etc.) in any mixture and capacity — similar in concept to JBOD – We saw in the video that this would be true of any SATA drives.  The Drobo does not support add on USB drives…but what if it could?  (Mostly said for a reaction from Chris Lux!)
   3. A single folder namespace (no drive letters) – We saw from part one that the Drobo presents one single volume to the WHS.  There is more testing that needs to be done when the Drobo goes over 2TB and that will come in the next review.
2. The Drobo runs very silent and very cool.  It is built and designed very well.
3. Adding and removing drives is simple and easy to do.  The unit itself does a great job of telling you when it needs more drives and where to insert them.  While a GUI interface is available, it’s not necessary most of the time.
4. The Dashboard tools that come with the Drobo are easy to use and give great information with adding and removing drives.  It is also easy to get a good look at the condition of the Drobo just from the front lights on the box.

Cons

1. At 80% full, the Drobo is not as responsive as when the drives are <80% full.  It does prompt you to add larger drives at this point however and upon adding drives, the unit responsiveness returns to normal.
2. The drives take a long time to format.  This is not really that big of a problem, since you can still move data onto the drives while the process is happening.
3. In the context of drive temps, it would be helpful if some SMART monitoring was built into the Dashboad – Advanced Controls.  I know Drobo is about easy, but this might satisfy some of the guys who like to tinker.

In Part 3, we are going to add more space and possibly explore some tweeking options that are available in the Dashboard controls.  There is more to come.

Watch the Drobo Review page for additional posts and updates.   Drobo and Windows Home Server

Jim Collison is a blogger and podcaster for HomeServerShow.com and TheAverageGuy.tv.

Full Disclosure – Drobo provided an evaluation unit with drives for this review.

Tags: Drive Extender, Drobo, Windows Home Server

Category: Home Server Storage, Review, Windows Home Server