Partition Capacity Problem (Dashboard 1.6.8)

I want to use a Drobo 2nd Gen for Time Machine on a Mac so I need to partition.

If I partition with Dashboard, the size of the partition is not reflected correctly in the OS. If I set the partition at 2TB, it is reported at 2,2TB by the OS. If I set it at 4TB, the OS sees it at 4,4TB.

If I partition using Disk Utility, the OS sees the correct size, i.e. 3TB is 3TB, but the Drobo and the Dashboard only “see” one partition and completely ignore the other one. The blue lights do not reflect the usage of the first partition at all.

I am running Dasboard 1.6.8 and Firmware 1.3.5. I believed that it might be related to the fact that I don’t have 1.3.6, but I can’t install it. I follow the instructions but it does not update. I have now confirmed that my drives do not have 4k sectors so that can’t be the issue in any event.

I tried shutting down and restarting, I reformatted several times in various ways using Dashboard or Disk Utility, performed resets, etc. I also uninstalled and reinstalled Dashboard to no avail.

I need the OS to correctly see the partition size to use Time Machine. I also need the Drobo to see the real capacity used so that it can work properly.

I have read somewhere that the blue lights will correctly report capacity if I turn off Dashboard completely. I actually would prefer not to have Dashboard running all the time, so I am going to try that next. It is going to take a while to copy enough data for the first blue light to hopefully light up…

I have wasted hours on this and I am getting very frustrated.

I am using 2TB Hitachi HD and I am connected by Firewire.

What can I do to solve this? Is turning Dashboard off going to solve the issue? And why is it that the OS sees 2.2TB if I format a 2TB volume with Dashboard?

I would suggest opening a support ticket with DRI. It’s been known for sometime now that there were issues with the OS reporting the correct amount of space left, however dashboard usually reported the usage correctly. I’m not sure whether or not this was actually addressed in firmware 1.3.6 , but I would go ahead and open a ticket with them anyways as you should always be able to update your device without issue.

I think that I understand why the Snow Leopard OS “sees” 4TB as 4.4TB. Drobo dashboard is probably binary-based units and SL is decimal.

1TB in binary is 1099511627776 bytes and 1TB in decimal is 1000000000000 bytes. So 1TB in binary is reported as 1.1TB in decimal.

Can anybody confirm this? If this is correct, I will simply partition with Dashboard and move on to other things.

In other words, can anybody confirm that it is safe to to use a partition created with Dashboard with Time Machine, provided that the partition is not larger than the physical space available?

All of this nonsense and aggravation stems from this KB article to the effect that you should use disk utility to partition for use with Time Machine. If this is not necessary, you should really amend this article (and also from the fact that 1.6.8 did not solve the issue of correctly reporting capacity of partitions created with disk utility).

Yes that is correct. Snow Leopard uses decimal. It was Binary on Leopard.

The KB article is to address customers who have let’s say 4 x 1 TB drives in their drobo. That gives you 2.7 TB available for used data but the customer would format for a 4TB volume size. The way time machine works, it will only see the virtual volume size and keep trying to write up to 4TB. Which will fill up your drobo to capacity and corrupt your data because TM will keep writing and writing and writing.

The article addresses that you should create a partition smaller than what’s available for data on your drobo so you don’t experience the above problems.

Note: The value you set for the Time Machine partition should be smaller than the Drobo device’s storage capacity. The amount of space remaining for use in the other partition will be the storage capacity minus the size of the Time Machine partition, not the virtual amount available in Finder and other Mac tools.

**Dashboard 1.6.8 did fix the issue of partitions created with disk utility not showing. If you are still experiencing the same problem, please open a support case.