No support for legacy authentication method in SMB or AFP

As previously mentioned, OS X Lion does not support logging into NAS boxes running Samba or AFP servers that employ the DHCAST128 authentication method. Apple documented this as a security update, in which they outright disabled DHCAST128 in Lion.

People who are running type of NAS system – FreeNAS or store bought boxes will not work in Lion!

Now some people have figured out a workaround to manually enable DHCAST128 in Lion, so if you don’t mind a little hacking in the system go ahead and use it. Otherwise try to enable NFS on your NAS. NFS is support by most NAS boxes running Linux. However, note that NFS does not provide any option for user authentication.

Option 1 – Hacking the OS

SMB/CIFS solution:

1. Upgrade FreeNAS to the latest stable build.
2. Setup your SMB/CIFS shares accordingly.
3. Go to Finder, click on Go->Connect to Server  or simply press command + K.
4. Connect to your server by typing smb://your.ip/hostname or use cifs://your.ip/hostname
5. Login, and you should be good to go.
6. If you don’t see the login pop-up, connect to smb://user:pass@ip  instead.

Do not use the link in Finder under the Shared category. It will not let you connect. It could be my settings somewhere that’s causing the problem, but so far I can’t figure out why it won’t let me connect straight from the Finder shortcut. However, the Connect to Server option works just fine.

Leave a comment if you encounter problems.

AFP solution:

1. Launch /Applications/Utilities/Terminal and do:

• sudo chmod o+w /Library/Preferences

• defaults write /Library/Preferences/com.apple.AppleShareClient afp_host_prefs_version -int 1

• Now restart your computer.
2. From Finder, select an AFP server, or use “Connect To…”.  This will cause the AFP Client to create the full preferences file
3. Launch Terminal again and do:

• sudo defaults write /Library/Preferences/com.apple.AppleShareClient afp_disabled_uams -array "Cleartxt Passwrd" "MS2.0" "2-Way Randnum exchange"

• sudo chmod o-w /Library/Preferences

• Now restart your computer.

To disable DHCAST128,

sudo defaults write /Library/Preferences/com.apple.AppleShareClient afp_disabled_uams -array-add "DHCAST128"

Credit for these command goes to Alexander Wilde, please visit his site for the original post. All credits go to him!

Option 2 Enabling NFS

In FreeNAS, go to Services – > NFS and enable 4 NFS servers.

then configure your NFS shares, the easiest way is to point the share to your main storage folder under and share all sub-folders underneath.

Configure NFS shares

Note that if you do not “Map all users to root” you will not have write access to the share!

Save and apply. Then go to Disk Utilities on your Mac.

Click on File – > NFS Mounts, click on the ‘+’ to add a new mount.

Configure NFS mounts in Disk Utility

Replace the IP and folder names according to your FreeNAS share. Then click on ‘Verify” to close the dialog and close the window to save your settings. You may be asked to login to your admin account in order to save the setting. The mount will be auto-mounted to your system at boot time.

After you set everything up in Disk Utility. Quit it and wait a couple of minutes for it to show up in Finder. Note that even though we mounted it to a folder on the Desktop, it will NOT show up! The easiest solution here is to go to your Desktop in Finder and create an alias to the mounted folder. Or, create an actual folder on the Desktop beforehand then mount the share to it.

This isn’t the safest approach since NFS in FreeNAS does not have any authentication support. But for my personal needs it’s actually quite nice, especially when NFS is about 30-50% faster than SMB in some cases. For many home networks, it’s the only way to stream HD videos over the air.

So please give NFS a shot if you don’t want to hack your system to use AFP!

Mac OS X Lion

Today, Apple shipped MacOS X Lion via the Mac AppStore. It sells for $29.99 USD, and it is topping the charts at the store.
This is the first time Apple went with a complete Internet-based approach to dealing with an OS upgrade. In fact, it’s the only time I have ever heard of an OS being sold strictly via digital download. Words on the street seem to suggest that if you go to an Apple retail store, they will install Lion for you through a local cached version of the OS. Thus, saving you the hassle of downloading 3.5GB over the net. It’s not really a life saver if you ask me, but it’s interesting to see how Apple is handling things for now, and the days to come.

My initial impression of Lion was fairly positive, but not overly impressed with the changes.

Pros:

1. No major compatibility issues with applications. Everything minus a few utility apps works fine on Lion out of the box, or requires a quick downloadable update. I’m guessing since most apps these days were written in Cocoa already, it wasn’t much of an hassle to fix the few kinks in Lion.
2. New Mail app is great! New UI with an option to switch back to the classic view if you want to.
3. System icons are mono-toned. This may be my personal preference, but I think colours can sometimes look a bit messy and disorganized.
4. System pop-ups, and transitions are super fast and smooth. Apple really took everything they learned from making efficient 2D effects on iOS to the desktop.
5. iTunes was rewritten for Lion in 64-bit! This is not really a Lion feature, but it sure has been a long wait.
6. New features – Air Drop, Versions, Resume , Full Screen, FaceTime etc.
7. No notable increase in disk space usage. It didn’t bloat unlike many Windows Service Pack updates.

Cons:

1. 

   No support for legacy authentication method in SMB or AFP

   Major compatibility issues with accessing Samba and AFP shares! This was certainly bad news for us who are using my FreeNAS build guide and are accessing files through either SMB or AFP. Apple decided that the authentication method – DHCAST128 was insufficient and they disabled support for it in Lion! This will break compatibility with all over-the-counter NAS boxes, including our DIY NAS. However, there are remedies that you can follow to work around it. Check out my later post.

2. Time Machine does not work over non-Apple network shares! This is a huge deal for people who use a thirdparty NAS box to host Time Machine backups. Unless your box can support the latest AFP stack in Lion, Time Machine will NOT work! You can put a sparsebundle on it… but it simply will not work. Time Machine only works through the latest AFP stack.
3. New features.
• Air Drop is Lion-only. There is no Air Drop app for previous versions of Mac OS.
• Versions is only an API that apps can be written on. It is not a system wide feature, and it is up to the developer to implement.
• Resume can be really annoying if you are using Safari and don’t want your web page views saved all the time! The setting to turn it off is also very hidden. You have to go to System Preferences -> General -> uncheck Restore Windows when quitting and re-opening apps.
• Full Screen is also app specific and requires the developer to provide support. Don’t know why they could just implement it some other way to resize the window to full screen.
4. Mail database took a good 15min. It was surprisingly slow! Maybe I had too much stuff in there.
5. No Java runtime in the OS. But the OS is smart enough to automatically download it when you need it, through Software Updates.
6. 

   Multi-touch gestures in Lion

   Super weird scrolling and gesture changes! The scrolling direction by default in Lion is the complete opposite of what you are used to. Apple call this the “natural” direction. But it’s really not so nature to me – natural is what I am used to. Don’t fancy me Apple. Thankfully, you can change this through System Preferences -> Touchpad -> uncheck scrolling directions. Apple also changed gesture to do Expose (now known as Mission Control), honestly this will need some getting used to. There are no settings to give you back the familiar Expose gestures. (ex. four finger down = show desktop, up = expose all windows, no more 3 finger scroll to get to the top of bottom of a page)

7. Minor annoyance – Launchpad shows all the uninstaller apps as well. This is terrible if you have Adobe CS installed. You will get a bunch of uninstallers listed with the apps and it’s almost impossible to find your apps! Yes you can do folders, but if you have a lot of apps… good luck sorting all of them. Launchpad is especially useless in this situation when a Spotlight search can open you any app with a few keystrokes.

To sum up, I’m not overly impressed with Lion. Especially the decision to drop legacy SMB/AFP authentication! I think if Apple didn’t sell it for $29.99 I wouldn’t even recommend it to people. Some of the changes are certainly nice, but nothing groundbreaking as you would expect from a major OS release. In fact, many of the neat features you saw during WWDC are app-specific and it will only benefit you if the developers choose to use it. Apple likes to build only the API and leave the rest to the developers, where from a customer’s perspective we like Apple to implement it in the system so all apps may take advantage of it. This is especially true regarding Versions. Apple could have improved the filesystem to support version control natively.

Having said that, I do think it is worth the $29.99 it sells for and Apple is certainly on the right path of revamping its OSes to stay ahead of the curve.

Previously, the FreeNAS project has stuck with the decimal 0.x scheme for build numbers. the latest nightly build we used for the DIY storage appliance was 0.7.2. Since then, the number jumped from 0.x to 8.0, with 8.1 baking in the oven.

Taking a deeper look inside, FreeNAS 8.0 is certainly miles apart from its 0.7.2 release, both in the OS architecture and the front end GUI.

• Based on FreeBSD 8.0
• Modular system design, allow for 3rd-party plug-ins
• Django based GUI, classic GUI still available
• ZFS parameters per dataset, such as quotas, were added
• LSI 6 gbps HBAs are now supported
• Migrated to rc.d init system
• CIFS settings that were mostly detrimental to performance have been removed
• VLAN interfaces are fully supported and can be created from the GUI or from the CLI menu
• Added the ability to edit ZFS options from the GUI such as quotas, compression, reservations on existing volumes and datasets
• Added the ability to create “stacked” ZFS configurations in the GUI as well as add devices to existing ZFS volumes
• Spare, cache, and log devices can now be added to ZFS volumes through the GUI

As highlighted above, I am most excited about the add support of ZFS features that will greatly benefit our cause to create a cheaper and more functional device to the droboFS.
FreeNAS 8.0 represents a more complete port of ZFS from OpenSolaris. The most exciting feature is the ability to add devices to an existing ZFS array. Although this has been available to the latest OpenSolaris systems, FreeNAS 0.7.2 did not support it.

To those of us who have been waiting for more ZFS support in FreeNAS this is perhaps too good to be true! So what is the catch? FreeNAS 8.0 BROKE config compatibility from past FreeNAS 0.7.x versions! There is no way of importing configuration from 0.7.2 to 8.0, so the backups are useless. There is also no way of safely upgrading from 0.7.x!

I’m not certain if FreeNAS 8.0 running from a USB stick can automatically recognize existing ZFS arrays created by 0.7.x. However, we need to keep in mind that ZFS version upgrades are PERMANENT. That means once you are on the FreeNAS 8.0 train, you cannot get off without losing all of your data.

In the next couple of weeks, I’m going to experiment with upgrading my 0.7.2 system to 8.0. The things I’m waiting for are more 2TB drives to backup my data on the NAS.

Please stay tuned, and comment if you have questions or insights to FreeNAS 8.0.

The Goal
The story here is simple – we are building a DIY storage appliance that is not only FASTER but CHEAPER than the Drobo. I have owned a 2nd generation Drobo for about 8 months. For the most part, it did its job. However, all the weakness of the device surfaced when I dug into the world of Network Attached Storage or simply NAS. I have written about my attempts to put the Drobo on my LAN …   http://frankleng.me/2010/02/11/droboshare-alternatives-tonidoplug-gigabit-switch/ I did not want to spend another $200 for the Droboshare! That setup worked for the most part, but performance was not even close to production-worthy.
I mean try to live with a 4TB NAS that transferred at 3-5MB/s… which is actually on par with Droboshare’s throughput… need I say more?

What I needed was:

1. Energy efficient, lower powered machine. (It’s a NAS after all, not a media center)
2. Able to let me swap a drive when it fails, and not lose data.
3. Able to expand, swapped out the smallest drive and replace with a larger drive.
4. Costs a lot less than $350USD. (that’s the price of the Drobo, not including drives)
5. Easily manageable, settings can be tweaked and system status can be monitored.
6. Speed, Speed, Speed. Must be able to sustain Gigabit throughput, even for larger files.

The Facts
Most BYOD (Bring Your Own Drives) storage devices on the market today do NOT offer the features that the Drobo does. The Drobo was never designed as a NAS, but rather a DAS (Directly Attached Storage), and it did that job fairly well. So if you are an average user who favour ease-of-use than anything else… then read no more… you are better off with the Drobo. However, if you are like me and you want that blazing fast performance for the smallest price tag… you have found the right place. =)

NAS devices are computers too. The basic rules do apply – the faster the chipset the faster the throughput; the more RAM the better, etc.

Lastly, and most importantly NAS devices’ throughput depend largely on caching and the CPU’s ability to translate between different storage and communication protocols.

Intel D510MO

The Hardware

CPU
It is really quite difficult to find a blazing fast computer by today’s standard without killing your electricity bill. Most high end processors run 100W + and even lower end chips easily go over 40W (That’s almost the same as the Drobo’s power consumption with 4 drives inserted… so it’s quite a lot for a single chip!) Thankfully, Intel created the Atom series of processors. Originally made for netbooks and mobile devices, the Atom series chips are Intel’s smallest and greenest – consume only about 10W. You can buy Atom from most local computer stores, but note that they are bundled with a motherboard and not sold separately.

I picked the latest generation, and the fastest Dual-Core Atom chip -D510 @ 1.66GHZ. This chip gives the equivalent performance of a Single-Core Celeron running at 900-1000MHZ but uses 1/4 of the power, TDP rated at 13W. Because the chip is so new, very few motherboard manufacturers have them shipped to stores. I grabbed the Intel D510MO motherboard bundle for $80 CAD.(It was the cheapest option I found, and had the same features as the more expensive ASUS and Supermicro boards).

RAM
The D510MO takes DDR2 memory, and  I happened to have two 1GB sticks. Obviously the more the better, DDR2 RAM sticks are super cheap nowadays and you don’t need the fancy ones. 2GB RAM – $30

Add-ons

Modded PCI SATA Controller

I want to talk about add-on cards because you will need one for this build. Like most Mini-ITX boards, the D510MO only has 2 onboard SATA ports and it’s not enough to have a more robust ZFS setup. Therefore, I searched online and bought a PCI-X/PCI SATA II controller card and gave me two more internal SATA ports. Later, I modded one of the the eSATA ports to SATA by replacing the connector head. The card was the SYBA SD-SATA2-2E2I – $36. There is a 4 SATA port version of the card, but I wasn’t able to find one at the store. I also liked the idea of having an eSATA port.

CHENBRO ES34069

Case
I went through 2 cases for this build. I originally bought the Chenbro ES34069 because it had 4 swappable drive bays. However, the proprietary power supply, the lack of space in the case and noise from the case fans(fans were not user replaceable as far as I could tell) eventually made me return the purchase.

The case requirement here is simple, find a small case (mATX or mini-ITX) that has 4 drive bays. Do note that besides the Chenbro case, there really isn’t an alternative that has swappable bays. So go spend the $200 and buy it if you want ease of access. The case I ended up using was the Antec NSK-2480 – $100. It has plenty of space for the two 5.25′ and 3.25′ bays and a 380W standard power supply. It has the best cooling arrangement I have ever seen in a media center case. Head over to SilentPcReview for some professional opinions.

Antec NSK2480

I also considered the NSK 1380 case, but spacing arrangement inside the case was nowhere near what the NSK 2480 had. However, the first does have much smaller dimensions.

Antec NSK1380

Drives
First of all, you will need a set of drives to store data and one other drive to host the OS. I have purchased 4 WD Green 2TB 5400rpm drives because they are quiet, efficient and more than fast enough for a NAS. However, do know that you will need at least 3 drives to take full advantage of ZFS. Also, the current version of ZFS does not allow you to add physical drives to an existing ZFS pool. Although you will be able to REPLACE one of the four drives for a bigger one, adding a 5th drive without rebuilding is not possible at the moment. This means if you started out with 4 drives, you will always have 4 unless you recreate your logic pool and lose all the data in the process.

I guess this is the only spot where Drobo may have an edge over our ZFS build. You can add more drives into the Drobo at any time until the slots are full. I believe Drobo accomplishes this by pre-populating its storage pool with virtual devices, and a virtual total size. That way, any new drive can just slide into these pre-made virtual slots without affecting the storage pool as a whole. Lastly, the ZFS development team has plans to resolve this limitation in the near future. So let’s stay tuned.

For the OS drive I decided to use USB sticks. They are much cheaper and much more energy efficient than having another disk spinning at 5400rpm to keep the system running. I used a USB port expansion cable to make use the connector on the motherboard and keep the sticks inside the case. Check out the picture and you’ll know what I mean. =p

Adapter with dual USB sticks

Accessories
The D510MO board does not have an IDE port to hook up a CD-ROM drive. It does support booting from USB. However, most OSes do not offer a .usb image for install. Therefore, I purchased an IDE to USB adapter so I could boot from my DVD drive. My IDE to SATA adapter was not recognized by BIOS for some reason… so please be aware if you are thinking about getting one of these things. It’s safer to get a SATA optical drive instead. I see them on sale now for under $20. Anyway, since FreeNAS supports USB images, there was no need for any additional accessories. (Note: Other OSes mentioned above will require a optical drive to install.)

Total cost: $246 (shipping included, taxes not included)

Next up… the software.  Turn the page.  =p

HOWEVER… I’m getting 3-5mb/s Write, and 3-20mb/s Read. The speed fluctuation is related to the limited CPU and I/O resource on the TonidoPlug. For a $550 setup (2.3TB) the speed just doesn’t make any sense. Even a 300mb file takaes 10min to write… this is clearly not a viable option for any power user.

After speaking to a friend, I was quite inspired by his ZFS rig that actually cost less and is capable of delivering 3x the speed I get. The rig’s 75W power consumption wasn’t too great in my books, but I’m sure by using something less powerful I can crank the wattage down.

My checklist for this rig:

• - Cheaper than the Drobo and TonidoPlug, in other words less than $400USD.
• - Efficient, low power consumption.
• - The rig must have at least 4 swappable drive bays. As it turns out, consumer grade swappable bays are prone to drive vibration. Especially when used with high speed drives 7200RPM+. Be warned.
• - Must be fault-tolerant like the Drobo.
• - Space must be easily upgradeable, again like the Drobo.
• - Must be faster than the Drobo, and is able to sustain read/write speed even for large files.

At first glance this looked to be a tough find, but the worry eased up after some research. It was clear that my rig will need to be in the mITX form-factor, and it will need an energy efficient CPU.

The slower Celeron chips caught my eye for a second, but it was the new Intel Dual Core Atom that shined. With a TDP (Thermal Design Power) of around 13W, the dual-core Atom D510 offers faster performance at a cooler temperate than the previous generation N330 it replaces. (FYI, TDP only measures the amount of thermal energy that need to be dissipated to keep it at an optimal temperature, it does not measure total power consumption). The D510 offers a fast front-side bus, and dual-core architecture clocked at 1.6GHZ. According to previous performance comparisons, a single core Atom running at 1.6GHZ is equivalent to a 900MHZ Celeron.

Therefore, I’m assuming the dual-core will performance similar to 1.2GHZ Celeron M chips. For the purose it is going to serve, it got a gold star in my books. Lastly, since Intel does not sell the Atom chip as  a standalone product, I was looking for a bundle with a motherboard.

Due to the low cost of these parts, most motherboards offered will only carry 2 SATA ports. That is a big NO NO for a NAS box! The good thing is that most of these boards do have a PCI slot for expansion, so you can put a SATA controller card in there to expand its ports. (Note that in order to have Sata II  3Gbit/s , you will need a PCI-Express based controller).

I eventually nailed my choice down to the Intel Atom D510MO bundle. It has 2 SATA, 7 USB, 1 PCI and 1 PCI-E mini slot. The board isn’t the most full-featured product, but it was cheap and made by the mighty Intel itself. Other alternatives from ASUS and Supermicro offer similar specifications for a higher price, and to be quite frank I don’t trust those vendors as much as I do with Intel. (Supermicro does offer a board for the D510 chip with 6 onboard SATA ports, but costs more than twice the Intel board). Price $80 CAD

The D510 uses DDR2 memory, but I already have 1GB sticks laying around. so no need to buy more. but they go for $30 nowadays.

Along with my Intel D510MO I ordered a PCI SATA II controller. The model number is Syba SD-SATA2-2E2I, and it was the only SATA II controller I could find with a PCI interface. I know I won’t be able to get full SATA II speeds, but I’d rather not play around with the jumpers on my older SATA II drives to get it to work. Price $36 CAD.

Lastly, I needed a small yet stylish case to house everything. I know my budget allowed me to have a case with at least 2 hot-swappable bays, but I really need 4 of them. The obvious choice was the CHENBRO ES34069. It comes with 4 hot-swappable SATA drive bays and either 120W or 180W power supply. The package I ordered from NCIX also included a riser card and a camera card reader. For more than $200 it wasn’t the cheapest option, but it certainly looked worthy and it had exactly what I needed. Price $ 207 CAD.

CHENBRO ES34069

Antec NSK2400

After testing the Chenbro case for a week, I must say that the swappable bays are not exactly what I expected them to be. They share the same flaws as many consumer grade screw-less systems… DRIVE VIBRATION and NOISE! Since each swappable slot was not held tightly enough, drive vibration can be heard quite clearly. (Same problem we have with the Drobo actually…) The two fans in the back of the chassis were also inaccessible by the user, and there was no speed controller connector to allow the user to adjust their speed. Therefore, you end up with a system that spins 100% RPM at all times – something the Drobo solved by adding thermal sensitive cooling fans. Lastly, the external power supply is proprietary! The cable that plugs into the chassis looks more like a PS/2 port… rather than a standard PSU connector. You know what this means… if your PSU on the Chenbro ever give out on you… you are going to have fun finding a replacement… then burn a hole in your wallet to pay for it.

So without anymore ranting… I introduce to you the final piece of the puzzle – Antec NSK2400. It costs half as much as the Chenbro, it has 4 drive bays – two 3.5 inch and two 5.25 inch. Click here for a thorough review from slientpcreview.com
I bought two 3.5 – 5.25 drive bay adapters to fit all four of my 3.5 inch SATA drives. Obviously the bays are swappable, but I don’t plan on having multiple drive failures everyday that I need to be swapping drives. =p

This case can accommodate up to mATX form factor, so it will make a good media center chassis as well. – Price $101.91CAD

Finally, the total came to $230 after shipping and taxes - That’s almost half the price of the Drobo, even after you add the cost of RAM.

As you can see, the case I decided to get was a bit more expensive than most. There are a lot of cheaper options out there, especially if you don’t need hot-swappable bays. Secondly, if you are adventurous DIY is another way to go. Check out the DIY project here: http://paulstamatiou.com/diy-200-dollar-pc-part-3 to build an awesome looking acrylic case for your NAS!

Please check back for Part 2 of this NAS adventure. My parts should be in next week, but since the case was re-ordered it might take some time before I can post updates. Please stay tuned! and big thank yous go out to all the people who tweeted and commented on this thread. Thank you for the interest. I won’t let you down!  =p

The droboshare adds NAS capability to the drobo for $199 USD, which is an insane price tag for what it is. I looked around the web and found two worthy alternatives – pogoplug and tonidoplug. Both are based on the same architecture – the Sheevaplug from Marvell.  (1GZ ARM cpu with 512MB RAM and 512MB Flash).

The Pogoplug is a widely popular product with their own backend service that will allows user to share data on the Internet directly from the NAS. However, I’m not a big fan of pogoplug’s closed platform, and the fact that all my data are routed by the pogoplug server. Eventually I ordered the tonidoplug which is cheaper and did exactly what I needed it to do.

The guys over at Tonido really tried to simply the setup process for the average user. There are still flaws and bugs, but the community is growing quickly and your questions do get answered.

The only problem with the Tonidoplug is that it cannot detect multiple LUNs on a single device. This means if you have multiple partition on your drive, the 2nd partition will not be recognized. Secondly, the maximum supported volume size is only 2TB.  These problems eventually killed the dream of using it as a droboshare…

However, these should be easy things to fix as long as the Linux kernel on the plug are recompiled to support these features… I have already made contact with one of the users on the forum who is looking into writing a system module to address these limitation temporarily.  I hope tonidoplug will come up with an official update soon.

They have huge potential to capture the droboshare’s marketshare.

Update: With help from the guys over the Tonido support forum we found  a temp solution. It’s not pretty but It sure does work! Read on…

Basically the idea is to load a more updated kernel with a USB stick.

You will need:

• TonidoPlug
• USB flash drive 512MB or larger
• Powered USB hub to connect drives

Install TonidoPlug firmware to a USB drive

1. Connect the USB drive to TonidoPlug. The USB drive will be automounted on /media/usb0. Stop samba server and unmount the USB drive before proceeding. To do this SSH to the TonidoPlug and run the following commands.

# /etc/init.d/samba stop
# umount  /media/usb0

2. Make sure the external USB drive is not mounted anywhere else. Check the output of the following command.

# mount
rootfs  on / type rootfs (rw)
tmpfs on /lib/init/rw type tmpfs  (rw,nosuid,mode=0755)
/proc on /proc type proc  (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs  (rw,noexec,nosuid,nodev)
varrun on /var/run type tmpfs  (rw,nosuid,mode=0755)
varlock on /var/lock type tmpfs  (rw,noexec,nosuid,nodev,mode=1777)
udev on /dev type tmpfs  (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts  on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
tmpfs on  /var/cache/apt type tmpfs (rw,noatime)

As you can see the USB harddrive (usually /dev/sdaX) is not mounted anywhere else

3. Format the USB drive partition. You are about to create EXT3 filesystem on the USB drive partition. Warning: This command will wipe all the data on the partition.

# mkfs.ext3 /dev/sda1

Note: If you have multiple partitions in your USB drive, you have to always use the first partition, because the TonidoPlug will boot only from the first partition of the external drive.

4. Once the formatting is completed, mount the partition on a temporary directory

# mount  /dev/sda1 /media/usb0

5. Download the root and modules tar ball from TonidoPlug site and place in the newly created ext3 partition.

# cd /media/usb0
# wget  http://www.tonido.com/downloads/plug/rootfs.tar.gz
# wget  http://www.tonido.com/downloads/plug/modules.tar.gz

Please make sure the checksum of the files match the following values

# md5sum   rootfs.tar.gz
958a32161e1daf1c79d88b1c6f6e85bf  rootfs.tar.gz
#  md5sum modules.tar.gz
c2b89c8dd681656427b27a2fc1db725f   modules.tar.gz

6. Untar the downloaded tar file onto the ext3 partition.

# tar zxvf rootfs.tar.gz
# tar zxvf  modules.tar.gz

7. Now stop tonido and copy the tonido directory from your existing internal flash disk.

# initctl  emit tstop
# cp -dpr /root/app/ /media/usb0/root/

Install a New Kernel

cd /media/usb0/
wget http://sheeva.with-linux.com/sheeva/2.6.32.8/sheeva-2.6.32.8-Modules.tar.gz
tar xzvf sheeva-2.6.32.8-Modules.tar.gz
rm sheeva-2.6.32.8-Modules.tar.gz
cd boot
rm uImage
wget http://sheeva.with-linux.com/sheeva/2.6.32.8/sheeva-2.6.32.8-uImage
mv sheeva-2.6.32.8-uImage uImage

Now reboot the plug and SSH into it. You should see the new kernel version in the SSH greeting.

Note that this method requires you to have a POWERED USB hub. Simply plug in the Drobo after the plug boots up with the new kernel and it will be auto-mounted to /media/usb0

A Big Thank You goes to mikestaszel for the help to accomplish this.