Swapped out for smaller drive, now its asking me to fill a new bay

I have have an 800fs that previously had 5x 3TB drives, with 3 bays empty. Drobo is set to single disk redundancy.

Last week, I removed one of the 3TB drives and replaced it with a 2TB drive. After quite a bit of time, the array finished rebuilding, and the device was usable again, as expected.

Today, I removed another 3TB drive and replaced it with a 2TB drive as well, leaving a configuration of 3x 3TB drives and 2x 2TB drives, with 3 bays empty. Instead of rebuilding the array again, as expected, the Drobo is instead asking me to insert a new drive into bay 6 which has always been empty. It also displays a warning that the Drobo cannot protect against disk failure until I have provided at least 2 drives for single disk redundancy.

Why is it doing this? I understand that by replacing my drives with smaller ones, I am reducing the amount of usable space - I want the array to simply rebuild again, reducing its size accordingly to work with the existing disk configuration. I do not want to add another drive to the device right now.

What are my options?

hi, it might be that a certain amount of free space needs to be present, or it wont be able to downgrade, but do you have any other information about the free/used space and % of space that dashbaord is reporting, as well as the number of blue leds that are lit?

I have the same problem. I have a Drobo-FS with 5 x 3TB drive and I am moving data to a new one. When I had over 3TB of free space I removed one of the drives. Since then the Drobo is asking me to add a drive in the empty bay and warning me that it cannot protect my data until I provide at least 2 hard drives.

As I have been removing data and the current status of the Drobo is Bay 1-4 steady green light and 3TB drives each. Bay 5 steady red light and asking to add a drive. 5 blue leds are lit on the front.

Total capacity is 8.15TB, used 4.00TB free 4.14TB.

I have no spare drives over 1TB to add to it.

How can I get the device to re-layout so I can remove the next drive?

hi can i check if you still have the drive you removed (assuming from bay 5?) or did you actually put it for re-use into the other drobo?

you might be able to add a spare 1TB into the empty slot, and to see what drobo and dashboard show you once it has been absorbed into the pack. (can you check if you are using single drive redundancy SDR or DDR dual drive redundancy?)

I used the drive in the new box.
I had tried a 500GB drive and left it in all weekend with no change.
I just put in a 1TB drive, received a blue notification. Bay 5 is showing a 1TB drive installed but is still solid red.

The unit is set to single disk redundancy (RAID5)

thanks for the info,

if it still has not changed, then it may be that some more space needs to be freed up.
what you could try to do, is to copy about 500GB of data onto the 500GB drive you have (which i assume is currently out of the unit and working ok and free to use?) and then once you are happy that the data was successfully copied, you could then try deleting that from the drobo. (you would probably need to hook up that 500GB drive somewhere else, such as inside a standalone usb drive caddy or something similar).

after letting things settle down a bit (and you can see the free space on dashboard slowly creep back up by that amount) does it then change the status? (something similar could also be carried out on the 1TB drive, but seeing as the 500GB drive might be available to use it might be better to start with that)

I have been moving data off the Drobo for the last week.
My plan was once enough files were moved giving more that 3TB of space on the Drobo I would remove one drive and let the drobo rebuild, install the drive in the new box and continue removing files doing this each time 3TB of space was available.

After the 1st time doing this, the Drobo reduced the total capacity reflecting only 4 x 3TB installed, but never performed a relayout.

As of rate now installed are 4 x 3TB a+ 1 x 1TB and Drobo is reporting
Total Space = 9.05TB
Used = 3.04 TB

I restarted the Drobo this morning and Drobo Dashboard saw initially that Used = 0TB and it slowly increased to the correct amount (about 3.4TB)

My biggest problem is that I was counting on the Drobo to rebuild after each drive removal and it is not. I have less that 1TB room left on the new box and still over 3 TB of data to move.

I have 4 solid green lights on the 4 - 3TB drive, 1 solid red light on the 1TB drive and 3 Blue LED.

thanks for more info,
if you can look in dashboard, can you see any more (free space) creeping back up (as the blocks become reclaimed?)

it may just be that you can not downgrade a certain amount in the current config of drives (but i think if the drobo is stil reclaiming any blocks, that might be taking preference over any downgrade)

The Drobo was always relaiming blocks. As I removed data the Dashboard’s status of the device was showing the increase in available space.

Last night the Drobo finally started a relayout. It waited until 84% of the total capacity was free 8.13TB total, 1.33TB used 6.80 TB Free. Rate now it says that Data Protection will take 129 hours (just over 5 days!), which is a rate of 10.5GB/hour, 180MB/min or 3MB/sec.

hi thanks for the info,
if nothing else is using the drobo i think the time estimate might actually speed up to a couple of days, but lets see how things go (usually its about 1day per 1TB of data to rebuild, minus any other actions or usage)