Size issue with Drobo FS


First sorry about my bad English

i have this issue on my drobo FS updated with last firmware (1.0.3). i have 4x 1TB western digital black. and see this pictures please

16TB :open_mouth: !!!

it’s same result with windows


Hey Shezon,

This is completely normal. As you’re obviously knowledgeable about UNIX I’ll give you the full run-down as I understand it:

/sbin/fdisk -l /dev/sda

Disk /dev/sda: 17592.1 GB, 17592186044416 bytes
255 heads, 63 sectors/track, 2138794 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

The Drobo uses “thin-provisioning”. What that means is that the OS sees a 16Tb block device, regardless of how much physical disk you have. The DroboFS then formats an ext3 filesystem onto the first partition of this block device.

The reason for that is simple. Re-sizing filesystems is a pain in the backside, especially when you start dealing with connecting those filesystems via cifs, iscsi, nfs, esata, fw, usb etc to other hosts.

None of those protocols (that I am aware of) support (well) hot changes to block device sizes.

So, the way that DroboFS achieves being able to do dynamic resizing is to pretend that the block device and filesystem is always 16Tb in size. The cleverness in the block device driver then worries about resource allocation.

From linux (nfs): 16T 69G 16T 1% /mnt/drobo