Drobo

Mac: Any way to get case sensitive HFS+?

Hi,

I’m a first time Drobo owner (Drobo S) and it seems to be working fine so far! I have it hooked up to a Mac running Snow Leopard. I have 5.4 TB of usable space (5 x 2 TB, with dual disk redundancy), with a volume size of 2 TB, which means my space is split out into three 2TB volumes.

I found http://support.datarobotics.com/app/answers/detail/a_id/43 which seems to say that there is no way at all to format a Drobo volume as case-sensitive HFS+.

However: My understanding is that aside from the last volume (which is where additional space gets added), nothing really funny is going on and the volumes pretty much show up as normal Firewire storage devices. Actually, now that I’m thinking about it, I may be confused – what I read may have said that it’s the last partition (within a volume) that’s special in that way.

So my question is: What would happen, theoretically, if one were to use Disk Utility to format all but the last volume as HFS+ case sensitive?

I could also do with some more education about how much “magic” is actually going on behind the scenes, really. How much does the Drobo have to understand about the filesystem format that the OS is using? I’m guessing it has to know “enough to be able to look at it and know what’s free space and what isn’t”, because it has to know which blocks actually need to be backed by real storage, and which blocks can be returned to the (Drobo-wide) free pool. Possibly “enough to be able to reorganize all the used space to the beginning”, if it ever needs to shrink something.

Actually, instead of me asking these kinds of questions piecemeal, what would be fantastic is if there is documentation out there that explains some of what’s going on behind the scenes. Is there anything like that?

Thanks!! (And if anyone from Data Robotics is reading this, thanks for a great product!)

Sorry to follow up to my own post – I was thinking more about this and eventually a theory occurred to me as to how this stuff might be working. I’ll post the theory as a separate thread, and then if it turns out my (new) understanding is correct, then this question will be redundant :slight_smile:

Drobo does not support HFS+ case sensitive. (I see you have another thread discussing the specifics).

However its reasonably easy to work around this.

I would format up the Drobo as HFS+ using the Drobo Dashboard as normal.

Next I would open up Disk Utility and create a new ‘sparse bundle disk image’. Once you select a sparse image you can then set a custom Size - say 16TB to match the formatted capacity of your Drobo. In here you can select the format to be "Mac OS Case-sensitive, Journaled).
Save it to your Drobo.

Now you have case-sensitive volume and its stored on your Drobo - just be sure to save your files on the mounted disk image instead of the Drobo disk.
The sparse bundle grows in size on disk as you add files - so works nicely with the drobo which does a sparse allocation of its own to pretend is has more capacity than you have on your physical disks.

One thing you may need to do once in a while is to compact the sparse bundle disk image in order to reclaim free space when you delete files. Once you compact the bundle it will free space it uses on disk - on the Drobo volume, and Drobo in turn will mark space as free on its internal disks.
Do to this first Eject/Unmount your sparse disk image then open a Terminal run the command
hdiutil compact /Volumes/Drobo/mydiskimage.sparsebundle