Drobo removing one HDD

So far I am enjoying using my drobo-fs.

I guess my question applies to all drobo’s.

So far I have only added hdds 4x1TB and 1x1.5TB.

What I’d like to do is remove my 1.5TB and put it as a second drive in my main PC. Is it safe for me to remove it? I am scared :slight_smile:

All lights are green, and the blue lights are a little over half way.

Drobo Dashboard indicates I am using 1.98TB out of 3.57TB capacity.

The only reason I am asking is that most youtube demo’s I have seen have always shown removal of the “smaller” and “faulty drive”. The 1.5TB is healthy and just wish to reuse it elsewhere.

yes, if you remove it - you will be back to being “at risk” of failure (i.e. if another drive fails you have an issue)

if you can enable dual disk redundancy - you should do so.

once you have dual redundancy turned on, then you can safely remove your 1.5 tb drive - drobo will tell you that you are not protected (it only means you are not protected against DUAL failures).

if it starts to rebuild automatically (it will do if you have space) then let it finish.

if it does not start to rebuild automatically then you may need to change back down to single disk redundancy in order for drobo to have enough free space to rebuild.

i hope that is clear :slight_smile:

Do I have to do dual disk redundancy to remove one of five drives?

If I remove the 1.5TB permanently and only wish to use the 4x1TB HDD will BeyondRAID recognize the 4 drives and give me single disk redundancy?

Are you saying I should do dual disk redundancy because the drobo may not rebuild/adjust?[hr]
I will do what you say, logically if something bad was to happen to one of the 1TB’s while removing the 1.5TB. Then it is the wiser procedure to follow.


I think with four 1TB drives and a 1.5TB drive with ~2TB stored you are at the point where dual disk redundancy won’t be possible after the removal of the 1.5TB drive. Assuming that you lose the capacity of two 1TB drives to provide redundancy you are only left with 2TB of usable space. If it allowed this configuration, this would put the Drobo into the place where it slows down to prevent overfilling, and the rebuild process may have problems, or as @docchris says it will anticipate the issue and drop back to single disk redundancy only.

1TB drives can be had for ~$60 and 1.5TB drives for ~$80. Given the inconvenience, the (albeit small) risk to your data during the heavy drive activity during rebuild, and the probably 24hour+ rebuild time during which time your Drobo will be very slow, if there’s any chance you could spring for another drive either to replace the one in the Drobo or to put into your PC I think you would be much happier…

At the moment it is doing “data protection in process” because I clicked dual disk redundancy. Do I have to wait until this is finished and then swap it back to single disk redundancy?

i was saying more that you should have enabled dual disk redundancy - because then when you pull one disk - you are still protected against a second failure.

if you have single disk redundancy, and pull a disk… then you are no longer protected, so if another drive fails during the rebuild, poof! its all gone. and you remain vulnerable until it has finished the rebuild.

Do not remove a drive while it’s in data protection mode.

Thanks I won’t. It has been running for 8 hours and I have another 6 to go. I should have just left it in single disk mode. Changing to dual disk leaves my drobo unprotected for too many hours.

If I wanted dual disk I should have done it from the start before I had all my data on it.

I wonder if I had a power failure right now going between single to dual, would my data survive? Maybe stick that in the best practices pdf.

changing to dual disk mode does not leave you unprotected at all - its ADDING another layer of protection - you are still protected against a single drive failure (otherwise i wouldn’t have advised you that upgrading to it was a good way to protect yourself!)[hr]
Once you have achieved your dual disk redundancy and its showing “your are protected” you can pull your drive - and then it will say you are unprotected - but it means you are unprotected against double failure - you will still be protected against a single failure (since you selected dual disk redundancy and have only failed one drive by removing it)

ideally it will start to rebuild automatically to being dual redundant on your remaining drives, but you may not have enough space.

you should therefore be able to select single disk redundancy and it will initiate rebuilding to a safe single redundancy state on your remaining drives

Wow it only just finished 30 mins ago putting it into dual disk redundancy state. Thanks for the info everyone.

In conclusion I am going to go out and buy a 2TB HDD instead.

I used the drobo calculator http://www.drobo.com/calculator/drobo-s/index.php and realise having it in dual disk redundancy, I should not remove my drive.

My used space is 1.98TB

sorry, i’m lost, i think you skipped a few logic steps

what about the drobo calculator tells you not to remove a drive?

the whole point is that with dual redundancy, it is safe to remove a drive?

I’ll admit I don’t fully understand how the drobo works.

Basically my actual “used space” on the drobo is 1.98TB.

With dual disk redundancy if I remove 1x1TB hdd, the “available for space” figure is 1.81TB.

Doesn’t that mean I won’t have adequate space after removing 1x1TB hdd?

There are three possible outcomes when a drive is removed:

  1. Drobo will go into relayout and “downsize” the available storage to go back to the fully-protected state (DDR or SDR).
  2. Drobo will not go into relayout and will be in a degraded protection (DDR) or unprotected (SDR) state.
  3. Drobo will tell you too many drives have been removed, the storage will go offline, and it’ll blink red at you until the drive is reinserted.

Which of the three happens depends on how much data you have stored on your Drobo and how much data a fully-protected Drobo without the removed drive would be able to hold. In none of the cases would data be lost, unless #3 happens and you cannot replace the removed drive.

In your case, since there would not be enough space to “downsize” it’ll simply go into degraded protection DDR (essentially SDR) state, since you have DDR enabled. Case #2 above.

You will not have less usable storage, you will still be able to access your data, and you will still be protected from one drive failure.

Thanks. That was good to know.