Dashboard and 24 TB volume ?

Docchris wrote yesterday : “if you fill up your 16tb - you will have to start slowly replacing the drives with 3tb drives”

and a little bit later “If you replace all your 2 tb disk with 3tb disk then you would be able to store 24tb of data (less what is used for protection)”

Exactly what I plan to do in my drobopro(s). BUT, my question is about the present 16TB volume I have created : will it increase to 24TB by some miracle , or must I re-create a new 24TB volume (after a back-up of all my datas, of course) ???

I made a test - I removed all my 8x2tb WDgreen and put 4x3TB WD and watched what was happening : nothing !! Dashboard is still making a 16TB MAXIMUM volume.

How can I make a 24 TB volume ?? Have I missed something ? No Dashboard update for the moment, only the 1.2.1 firmware update I made 4 days ago (by the Dashboad updater, not any problem on my 3 drobopros connected by iSCI to my MacMini)

The same problem will come again soon, I red some news about 4 TB drives and even 5 TB drives - it will be then a 32 TB volume or a 40 TB volume.

Coming from France, I apologize for my english.
Thanks a lot in advance for any answer.

I have the same question.

Thanks a lot in advance for any answer.

16Tb is a limit for the volume size

if you have more actual space than this - then drobo will automatically create a second volume to allow you to put additional data on your drobo (NOTE: this isnt quite right - see the final part of my post below - i forgot you had a drobopro - but still read them all in order anyway :slight_smile:

with 24TB of space - drobo will create a SECOND 16Tb volume - and then you can put a maximum of 24tb of data spread across both volumes.

this will be fine up until 32tb of space

when you put in bigger disks to get 33tb of space - drobo will create a THIRD 16Tb volume - and even then when you have 3 x 16tb volumes - so ti looks like 48tb - you will still only be able to put 33 tb (your actual space) across all the volumes[hr]
with older operating systems the maximum volume size is 2tb - so people would have 4 x 500gb disks - for 1.5tb of space - and a 2tb volume and be fine

then they would replace those disks (one at a time) with 4 x 1 tb disks - for 3tb of actual space

and be puzzled why drobo had made a second 2tb volume

but it was so that they could use all 3tb of their real space - which you woudlnt do with a single 2tb volume - but you could with a second 2tb volume.

then peopel still get confused because they have 2 x 2tb volume - so it looks like 4tb of space - but they only have 3tb worth of disk space

but you can put your 3 tb onto your 2 x 2tb volumes how ever you like

so you could fill up one volume and have 1 tb on the other volume

or you could put 1.5 tb on each volume

whatever you like

then when they replaced those 4 x 1tb with 4 x1.5tb - they would have 4.5tb of actual disk space - so their 2 x 2tb volumes still werent enough to let them fully use that space - dso drobo would create a third 2 tb volume

i hope that makes sense?[hr]
BUT - since you have a droboPRO (ive just realised) you can control your volume creation (its automatic on smaller drobos and you dont get a choice)

on your drobopro right now - you can create a second 16tb volume if you want - or an 8 tb volume - you can have up to a maximum of 16 x 16tb volumes - and you could create them all right now if you wanted to!

the total data you put on those volumes can still never be more than the actual disk space you have available - but you can create upto 16 volumes - and choose each of their sizes yourself on a drobo pro

Thxs a lot Docchris.

What a pity - What a waste of disk space and a lot of volumes in the finder to manage - I hope DR is preparing a new Dashboard version, able to format a 24 TB volume.

its not a waste of disk space? there is no disk space wasted at all

i suspect just a fairly basic firmware thing

“you have a droboPRO (ive just realised) you can control your volume creation”

I always thought I can format several volumes INSIDE the 16 TB capacity, for example, one volume 8 TB + another 4 TB + a third of 4 TB , but I never thought i could pass over this limit.

So, if I understand well, you say that I can right now create a second 16 TB volume even if I have still only 8 x 2 TB drives presently inside my drobopro ( I have not yet added any 3 TB - I was waiting a dashboard update ) - It seems to me impossible - I’ll add first some 3 TB drives and see what happens.

About this update, I have sent a question to the DR support and I hope to receive an answer by mail soon.

yes - its called thin provisioning

think about it - if you have 4 x 1tb drives and 4 x 2tb drive s- you can still make a 16tb volume - you just couldn’t put more than 8Tb on it !

volumes and partitions are the same thing (for drobo’s puposes)

and the volumes sizes are separate from the physical space on drobo

you could put 1 x 1tb disk in your drobo - and then make 16 x 16tb volumes on it

another question : I have 10 TB of datas on these 8x2 TB WD in my drobo - they are back-uped on external 1TB drives in 4 eSata Sonnet Fusion 500p.
What do you think the quickiest ?
1 - add one 3TB to my drobo, wait reconstruction, then add a 2nd 3TB, wait…, and so on for 6 x 3 TB total
2- remove all the 8 2TB drives from the drobo, put 6 3TB and format 2 new fresh 16TB volumes - then copy the back-ups ?

Have you had such experience ?

Definitely option 2.

I received DR answer : “Thank you for contacting support. To answer your question we are always looking to add new features to Drobo, for now this is being looked at so I do not have a solid answer for you. If you put 8x 3tb drives in Drobo this will give you ~18tb of space for data, the balance over 16tb will be put into a second volume.
Let us know if you have any other questions or concerns.”

Just FYI, depending on file system choice, not all file systems can format up to and beyond 16TB. For example, if you choose FAT32 as your file system, you are limited to 2TB regardless of the thin provisioning that Drobo can provide. VXFS for VMware is also limited to 2TB. Just a point to remember.

even ones which theoretically support going beyond a certain limit - often “break”

chkdsk doesnt run/complete successfully on volumes 8TB & over

but then with 3TB the largest single disk you can buy - i doubt they tested chkdsk on 16TB volumes nearly as much as on the volumes 99.99% of users will be using

As said, you are much better off swapping all the discs in one go. I had a DroboProFS with 8 2TB drives. I replaced them all with 3TB drives and copied the data back over. It took less than 5 days. On my second machine I swapped each 2TB drive for 3TB drives one at a time and it probably took over 2 weeks. My third DroboPro is in an offsite location and I have just put in the first replacement 3TB drive. That unit is going to take a long time to do as I only can swap a disc when I am on site.

I am tempted to buy another DroboPro just to soak up all these 2TB drives I am throwing off.

I see on one of my units that I have 15.8 TB used on one volume (97% full). I hope that the unit will allow me to do a ‘logical’ move to the second volume and not copy all the data slowly. A full 8 bay drobo with 3TB drives has maximum storage of 18.59 TB of storage, so it almost all fits in one volume anyway.


i suspect it will be very slow - windows will treat it as a separate volume (which it is) so will be writing to drobo - as far as drobo is concerned - which will be deliberately speed limited at 97% full

The Drobo is 84% full at 15.58TB, it is the volume that is 97% full. As I will be writing from the full volume to an empty one I hope I will not get hit with the slowdown.


oh i see!

well you wont get the deliberate slowdown - but i suspect you will run into the fact that simultaneous reading and writing from drobo is slow.


you are proposing doing EXACTLY what i was doing which sent my drobo into an unsuable reboot loop

the problem is that moving like that is essentially writing new data while deleting old

and drobos garbage collection wasnt fast enough (well nto as fast as the move operation) - so it ran out of space (as in the internal file system it uses ran out of free blocks)

it still showed as having 15% free / 85% in use - but because the garbage collection hadnt flagged the blocks as free yet - it all went horribly wrong

I had just started the move but I have cancelled it after reading your experience. You were also right about the speed, it was around 6MB/s. I will delete the folder and write it from a different drive.

I appreciate your timely answer, you may have saved me from a disaster.



ianspector, exactly the problem I was wondering about - simply solved by copying a part of the external back-ups into the second 16TB volume and then deleting from the first 16TB volume - faster and more simple