My 8TB ext3 Drobo LUN on Ubuntu 9.10

i’ve already written a post that gave the folks at Data Robotics a hard time for not officially supporting Linux.  (It’s been in “beta” for well over a year, maybe two — and they don’t support LUNs bigger than 2 TB on ext3.)  I needed a LUN bigger than 2TB, so I was a bit upset.  Well, I’ve got my 8TB LUN and I’m happy.

The first thing the folks at DR would want me to say is that what I’m about to describe is totally unsupported and untested by them.  They advised against me doing it for that reason.  But since they stopped short of saying “we tried it and it didn’t work,” I went forward.  They told me that if i was going to do it, make sure I had a good backup.  LOL.  The guy that wrote that obviously didn’t know who he was talking to.

From what I’ve read, the appropriate drivers and fixes are in there as of Ubuntu 9.10, which I just happened to be running!  That may have been an important part of the puzzle.  I’m also using USB for now, as I don’t need the performance of Firewire yet and the firewire PLUS 8 TB is what have given some people fits.  Since I didn’t have a backup of my 8 TB LUN yet, I thought I’d wait on FW for now.  (I have a backup now, though.)

How to get the 8TB LUN is easy.  I followed the steps on this guy’s blog entry, which are as follows (liberal cutting and pasting from from his blog). 

One step I did was to set the unit back to factory defaults before doing this, so that everything was nice and clean.

Use the drobom command (which is an unsupported tool you can here) to set the LUN size to 8TB:

$ sudo drobom setlunsize /dev/sdd 8 PleaseEraseMyData
8 PleaseEraseMyData
You asked nicely, so I will set the lunsize to 8 as you requested
set lunsize to 8 TiB
Done... Drobo is likely now rebooting.  In a few minutes,
  it will come back with the new LUN size.

Use parted to set the disk label to gpt and create a partition of 8TB:

$ sudo parted /dev/sdd
GNU Parted 1.8.9
Using /dev/sdd
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) mklabel
New disk label type? gpt
(parted) mkpart ext2 0 100%
(parted) quit
Information: You may need to update /etc/fstab.

Format the 8TB partition:

$ sudo mke2fs -j -i 262144 -L Drobo -m 0 -O sparse_super,^resize_inode /dev/sdd1

Now all you have to do is mount it like any other filesystem in Linux.

My backup

I needed another 8 TB LUN to serve as the backup destination, but I didn’t want the backup to also be on an experimental filesystem.  So I used the HFS+ filesystem on MacOS to create a 16TB thin-provisioned LUN (as I only have 6 TB of disk).  I then used the rsync method documented in this blog post to make the backup.

Happy now!

----- Signature and Disclaimer -----

Written by W. Curtis Preston (@wcpreston). For those of you unfamiliar with my work, I've specialized in backup & recovery since 1993. I've written the O'Reilly books on backup and have worked with a number of native and commercial tools. I am now Chief Technical Architect at Druva, the leading provider of cloud-based data protection and data management tools for endpoints, infrastructure, and cloud applications. These posts reflect my own opinion and are not necessarily the opinion of my employer.

One thought on “My 8TB ext3 Drobo LUN on Ubuntu 9.10

  1. Daniel de Vries says:

    I’m considering EXT3 and an 8GB LUN on my gen 2 Drobo as my primary backup. It would we great to hear what your experience with this setup has been 1 year on.

    Would you recommend it?

    — Dan

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