Alternative filesystems?

I just received my DroboPro a few days ago and have been working on setting it up in CentOS. It’s been a bit of a pain to setup so far, but I have finally reached a point where I’m ready to format everything.

By default, the Drobo splits the drive up into 2TB devices, /dev/sdc, /dev/sdd, etc. I can reset this so that I have it split into 8TB or 16TB devices. However, EXT3 only supports up to 8TB volumes from what I can tell. I would like to have one large volume for all my data - which would be about 9TB. However I don’t see how this is possible with EXT3. So I’m wondering if I could try a different filesystem. I know it’s not officially listed as supported, but has anyone looked into using something like XFS? It’d be ideal for what I’m doing (video archiving). But I don’t know if the DroboPro would handle it. Anyone have any experience with this?

Also, any idea if there will be true Linux support or at least an option for dual disk redundancy in the future? I was quite surprised when I realized that an enterprise/business product like this one didn’t offer full Linux support out of the box.


Have U tried Smart Volume? That’s another “enterprise feature” uniquely available in the Pro but I doubt it CentOS will support that. The DDR & Smart Volume work well in our Windows Server environment. Pls kindly let’s us your outcome. TIA

Smart Volumes are a feature of the Drobo Dashboard so they’re not available on Linux. Our main concern is getting a file system that will be reliable, fast, and support large volume and file sizes. XFS appears like it’s exactly what we need. But I’m hesitant to create an unsupported file system on the Drobo because we also can’t really risk data corruption.

to avoid a great deal of pain do not use volumes > 2 TiB. Use ext3 ONLY!

You should read this thread:


and this:


If what I’ve read is true then I’m sorely disappointed in my Drobo Pro - it offers not much more than a standard raid array. I figured that there would be basic Linux support out of the box. I mean, it’s advertised as a “business class storage array” yet it doesn’t support one of the most common server operating systems.

The data sheet claims that Linux support is in beta. This leads me to believe that there is an official drobo dashboard for Linux in development, or was in development at some point in time. Not just an open source program like drobo-util. So my question then is, what has become of it?

It might be possible to use LVM (Logical Volume Management) in Linux to make multiple Drobo volumes look like one big volume to your system. Before I got my Drobo, I had a Linux box with eight physical disks in it, which I set up using LVM so that I had a boot disk plus one big volume that lived on all seven of the remaining disks. Is anyone out there doing this? Can anyone from Drobo comment as to whether it will work?

The second Google groups link seems to imply that it doesn’t work. I suppose I could experiment with LVM as well as tweaking the filesystem and LUN size. But the signs now just don’t look good.

Sorry, I didn’t follow those links initially.

Its clear that Linux support is “in beta”. Its been that way for a long time. No Dasbhboard or EXT3 volumes larger than 2TB are signs of “betaness”. That doesn’t mean Drobo doesn’t work under Linux, it just proves the disclaimer that it is in beta. Google products have gone years in beta before graduating. I bet Win and Mac users are by far the majority of their customers. Duh, I state the obvious. Almost all the IT folks I know say “Linux” is synonymous with “support yourself”

If I were Data Robotics I would have a difficult time justifying the current support as beta. Beta versions are intended to be feature-complete or near-feature complete. That is definitely not the case with Linux support right now. There is no official dashboard, limited volume size, and not all features (dual redundancy) are available. Instead there’s an open source application developed by someone outside of the company that provides some, but not all of the features. I think the marketing team went overboard be

For info, as of RHEL 5.1 / Centos 5.1, 16TB volumes are officially supported with ext3 systems.

I don’t yet know if the Drobopro limit is 8TB or 16TB though…

[quote=“Switcher, post:9, topic:561”]
Its clear that Linux support is “in beta”. Its been that way for a long time. No Dasbhboard or EXT3 volumes larger than 2TB are signs of “betaness”. That doesn’t mean Drobo doesn’t work under Linux, it just proves the disclaimer that it is in beta. Google products have gone years in beta before graduating.[/quote]

I like Google’s definition of beta more: “it’s not complete, but you can very well use it, and we’re constantly improving it”.

I gather you are referring to an announcement from Redhat that RHEL supports 16TB ext3. That isn’t the issue. Drobo is data aware. The firmware has to support 16 TB LUNS, and it does not. The only linux support that is in “Beta” is for ext3 file systems <= 2 TiB.

I have asked such questions to my contacts there many times, I have never heard such support. We have independently repeated tests (see the second link in my previous post), which have demonstrated failure to act properly with LUNS > 2 TiB. We cannot obtain follow-up on these documented, repeatable test cases because ‘linux is not supported.’

This device would be EXTREMELY COOL if they could get over this limitation… ideally with ext4 and support for ATA TRIM / SCSI DISCARD.
As things stand, it’s kind of cute, but of limited usefulness.[hr]

bias alert & disclaimer: I wrote drobo-utils and claimed the bounty :slight_smile:

DRI posted a bounty for open source developers to build an open source dashboard, with a GUI, a line-mode interface, and an API. This level of access is superior to what is available on other platforms (what is your CLI on windows, or programming API on the Mac?.) Drobo-utils was developed to claim the bounty, and DRI was true to it’s word. So they got a fully featured dashboard for less than what they would have paid for maybe a week’s labour. Pretty smart on their part if you ask me.

It was win-win, because I wanted a dashboard on linux anyways, sometimes the spirit is willing, but flesh is weak. But the prize was a very encouraging carrot to make me stick with it.

It is also win-win because the “right” way to do things on linux wrt driver downloads, is not to have the user download anything at all. While drobo-utils now has 2500 downloads from sf.net, what is more important is that it is now included in the standard repositories of the next releases of Debian and Ubuntu. ( installation for Ubuntu 9.10 is now:

apt-get install drobo-utils

.) No download or company maintained repository required. DRI is now leveraging open source. A little more packaging work (any volunteers?) should get it into Fedora, and thence into RHEL in a year or so. Getting it into distributions is the ideal, not some company maintained proprietary tool.

AFAIK, their intention was to obtain a linux dashboard through the bounty, and they did. I think they were somewhat disappointed at it being in python/QT, which is perhaps more dependencies than they would have liked, but it is a 90% solution, for 10% of the effort.

I think they played the part about the dashboard perfectly (but I might be biased on this point! :slight_smile:

The thing that’s sad is the limitations in their firmware. This thing could be wickedly great, if only…

If I were Data Robotics I would have a difficult time justifying the current support as beta. Beta versions are intended to be feature-complete or near-feature complete. That is definitely not the case with Linux support right now. There is no DRI-developed dashboard, limited volume size, and not all features (dual redundancy) are available. It really is little more than a giant RAID array. I think their marketing team got a little too excited and decided to throw “beta” into the specs. In reality, it’s closer to an alpha. Or perhaps even unsupported, considering that they don’t offer any official support for Linux as things are now.

I find this a little frustrating/annoying, because the DroboPro is advertised as a business-class product. Linux may not be popular in the consumer space, but businesses run Linux servers all the time. So to say to a business person that your product has beta Linux support yet doesn’t provide anywhere near the number of features as Windows/OSX version, well I find that to be more than a little misleading.

I must admit that I am also at fault here for not reading more carefully about Linux support. I saw the “beta” text and figured that it would be Good Enough. Nope - I should’ve looked into it a bit more. Oh well, I have it running on an OSX machine now. Not exactly as I would’ve hoped - down the line this will cause a few issues when I have to backup data from two machines instead of just one, but I guess it will work for now. I’ll just hope that true Linux support is introduced eventually.

Philobyte, I’m glad to hear about the bounty. I wasn’t even aware of it. Congrats to you then. My experience with Drobo-utils was a good one. Sadly it didn’t offer all the features I needed, but I’m sure you’re not entirely to blame for that. Thank you for developing a Linux Dashboard app - I’m sure it is useful for many others with circumstances not completely like mine. I hope that eventually you get a bit more support and are able to introduce additional features and overcome the firmware/filesystem limitations.

In the Drobo FAQ, it mentions 2TB volumes but also states larger volumes work.

I did some tests around the end of July 2009 and found a definite problem with free space not being recovered. I reported this as a bug and getting past tech support, got a response from one of the DR tech or firmware guys.

Among other bits, he stated:
‘We have not heard/seen this problem before.’

No implication that 8TB was not a useable size or it was in any way outside the firmware design spec.

My impression is that front line support automatically bounce anything that mentions Linux, so the real tech guys are not receiving useful bug reports and feedback.

I’m presently waiting to start testing again and hoping that the mention of ‘Corrected several issues with Volume Management’ in the Drobopro 1.1.3 Firmware notes relate to the Ext2 bug…

This knowledgebase article doesn’t say it won’t work, but says they don’t recommend it.
and this one agrees, while this other one seems to imply (some) customers have had success and gives pointers on requirements…

Still, it all seems pretty iffy. I’d wait until things settle down. Drive fault-tolerance isn’t much use if the filesystem itself goes haywire.

fwiw, DRI published some info about the option setting interface (for dual-disk red. ip-address, etc…) in August/September. The next drobo-utils version will hopefully support it. The other thing missing is alerts. If there is something else missing, please pipe up.

It isn’t a design problem, because the linux-based droboshare IS supported with larger LUNS and other file systems. It’s sad, because it must be >99% there. Some people have tested larger LUNS and they don’t work on the linux versions we tried (RHEL, Ubuntu 8 & 9), the firmware already supports larger LUNS, it’s really some specific problem with ext3… It is likely a matter of setting things up, properly instrumenting things and gradual debugging, which sounds expensive…

They could really change the picture completely with ext4 support… ext4 Max. file system size is 1 exabyte (EB - 1 million TB), which should keep people happy for a while at least. They knew they had a limitation with the original Drobo’s , and the PRO’s max. LUNSIZE is 32 EB.

Is EXT4 related to, or based on ReiserFS?

“Ext4 is the evolution of the most used Linux filesystem, Ext3. In many ways, Ext4 is a deeper improvement over Ext3 than Ext3 was over Ext2. Ext3 was mostly about adding journaling to Ext2, but Ext4 modifies important data structures of the filesystem such as the ones destined to store the file data. The result is a filesystem with an improved design, better performance, reliability and features.”*

They add the concept of extents (which is what the X in XFS stands for) to give far higher efficiency at large file size. that kind of changes everything, in terms of on-disk layout. It’s a one-way upgrade, not downwardly compatible.