Philip Homburg

Troubleshooting RIPE Atlas Probes: USB Sticks

Philip Homburg
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Some of the third version of RIPE Atlas probes have recently had an issue with their USB sticks. We're investigating what may be causing this issue and have a possible solution, outlined below. (At the same time, we're also looking into a new hardware solution for the future.) If you've had trouble with your probe, please follow these simple steps. RIPE Atlas users everywhere will thank you for getting your probe back online - and we will, too!


The issue

The USB stick on the version three (v3) probes is used to store both the operating system and the measurement data. In some cases, the filesystem on the probe can be corrupted, resulting in an unusable operating system. In turn, this causes the probe to remain "disconnected" from the RIPE Atlas back-end infrastructure.

Below we outline some steps to take to try to fix this issue, but it's important to note that the filesystem can always become corrupted again, so if you do run into problems with your probe disconnecting in the future, please repeat these steps.

How to fix it

Solution 1

As a backup, if there is a problem with the USB stick, the probe hardware itself has a mini-operating system that enables it to download fresh firmware and save it on the USB stick once it is available again.

In order to activate this last-resort option, the probe must be booted WITHOUT the USB stick. If you've already tried this and you're still having issues, please jump to Solution 2 below.

NOTE: This must be done on a network with working DHCP! It will NOT work if you have configured your probe to use a static IP address, because this mini-operating system does not have access to any statically configure IP addresses or DNS resolvers. If you have configured your probe to use a static IP address, the only thing you can do is move it to a network with working DHCP.*

Please follow these simple steps (these are the same instructions you'll see on the "Status" page):

1. Unplug the probe from its power source
2. Remove the USB stick from the probe
3. Plug in the probe WITHOUT the USB stick
4. Wait for ten minutes
5. Insert the USB stick

What will happen

Once the probe reboots, it will report the fact that it doesn't have a USB stick to the central RIPE Atlas system using a so-called "SOS" message. (You can see SOS messages on your probe's detailed information page under the "Network" tab at the bottom of the page.)

After ten minutes, it is safe to re-insert the USB stick.

Once the probe recognises that that the USB stick is present again, the process of downloading the fresh firmware  will begin. However, please note that this can take up to an hour to complete.

* If the probe was configured to use a static IP address, it will fetch it automatically. When the probe is listed as "connected" again, it is safe to move the probe back to its original location. However, please note that we advise configuring your probe to use a static IP address only if you feel it is truly necessary to do so.

If the probe is still not connecting, advanced users may want to completely wipe the USB stick on another computer and try following these steps again.

Solution 2

If your probe is still having issues with its USB stick, you should see a message under the "Status" tab on your probe's information page (you can see this by going to "My Atlas" and clicking on your probe's ID number).

my atlas

The error message will be about not detecting a flash drive or about having a read-only flash drive (see examples below).

no usb detected

read-only usb

If this is the case, please follow the instructions below (these are the same instructions you'll see on the "Status" page in both cases):

1. Unplug the probe from its power source
2. Remove the current USB stick from the probe
3. Plug in a new, brand-name USB stick that is at least 4GB in size (it does not need any preparation but its contents will be erased so make sure it does not store anything crucial)
4. Plug in the probe
5. Wait at least 30 minutes for the probe to initialise the drive and upgrade its firmware

Hopefully that will solve the issue and you will see your probe listed as "connected" again within an hour of the stick re-initialising.

Other possible issues

If neither of these has solved your problem, your probe will still be listed as "disconnected" or "abandoned".

When we have information about what might be wrong with your probe and detect a particular error, that information will appear under the "Status" tab on your probe's information page (you can see this by going to "My Atlas" and clicking on your probe's ID number). Please note that it takes up to four hours for probes to report an issue and for relevant information to appear on the Status page.

status tab

The "Status" tab on your probe's information page will report information about suspected issues and give advice about how to fix them

Of course, you can always contact us with questions at: atlas [at] ripe [dot] net or leave a more general comment below.

Thank you for your commitment

We really do appreciate the effort that our probe hosts put into keeping the RIPE Atlas network strong by keeping their probes connected. We couldn't build the world's largest Internet measurement network without you!

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About the author

Philip Homburg currently works on the measurement code and other firmware that runs on the RIPE Atlas probes and anchors. He received a PhD degree in computer science from the VU University, Amsterdam. During his PhD studies he designed a wide-area distributed system called Globe. He also worked on the security of mobile phones in the EU FP7 project WOMBAT, MINIX3 (device driver crash recovery), and an advanced disk abstraction layer in the Logical Disk project.

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