Technical FAQs

• 1. What might I want to find out before starting?
  • 1.1 Is it safe? – See BOINC FAQ: Security
  • 1.2 How long will it take?
  • 1.3 Why are the work units so big?
  • 1.4 Do I need to be on-line all the time while the software runs?
  • 1.5 Can I Suspend the experiment?
  • 1.6 How do I uninstall the software?
• 2. How to Get Started
  • 2.1 Where should I start?
  • 2.2 How do I know when I have got it set up and running properly?
  • 2.3 Why are some work units only available on one operating system?
• 3. About the Experiment
  • 3.1 What does the CPDN experiment do?
• 4. About running CPDN
  
  • 4.1 How many experiments does the software run?
  • 4.2 How much data is sent each way and how frequently?
  • 4.3 How much disk space do the models take up?
  • 4.4 Should I upgrade to BOINC from CP classic?
• 5. Problems running CPDN
  
  • 5.1 Why is there data left on my disk?
  • 5.2 I cannot complete by the deadline
  • 5.3 Why have I got a crazy time to completion?
  • 5.4 Why won’t it do anything?
  • 5.5 I’m running BOINC, but I’m not getting any tasks
• 6. Performance issues
  • 6.1 Timeslicing between BOINC projects
  • 6.2 BOINC GUI display tabs
• 7. Questions, Problems and Discussion Forums

1. What might I want to find out before starting?

1.1 Is it safe?

See BOINC FAQ: Security on the BOINC Wiki.

1.2 How long will it take?

This depends on how fast your machine is and how often you switch it off and also which model you are running.

CPDN runs experiments using 2 types of climate models – Global Climate Models and Regional Climate Models. When the project started, we mostly ran global models looking at long timescales of decades, but more recently we have been running regional models looking at much shorter time periods of months to a few years as part of our Weather@Home series of experiments.

The long, global model experiments take up to several months to run. The shorter, regional model experiments are much smaller and take between a few days and a month to run.

More specifically, for the models used in our Weather@Home experiments:

• HadAM3P takes 4.5 days on average (for a 1 year work unit)
• HadCM3N takes around 30 days (for a 10 year work unit)

1.3 Why are the work units so big?

How big are the workunits?

Compared to other projects, the models we use are very big.

Couldn’t they be made smaller?

CPDN workunits are a Climate Model that runs for between a few model months and many model years depending upon which model is being run. Trying to timeslice a model would make it very inefficient because you have to wait for the results of the first timeslice before the second timeslice can be started. So it doesn’t help and you would have to move around a lot of large data files. Also, it is nice to see a whole model evolve rather than only part of it.

That’s enormous – does that mean I won’t get credit for ages?

No, you will get credit for each trickle and there are around 100 trickles in global models. So at worst you only have to wait for about 12 hours to trickle. The stats updates are currently once per week.

Also, you do not have to wait for someone else to validate your work.

So how long do these Trickles take?

In CPDN the work units are a complete climate model. It stands alone and the project needs lots of slightly different models. The models are further subdivided into trickles, and timesteps.

A timestep represents a 1/2 hour of model time (not real time). Every 10,802 timesteps your model will trickle (report).

You will not see credit in your stats until after the first stats update after your first trickle has been uploaded, then your credit will increase with each stats update where you have uploaded one or more Trickles. Stats updates are currently run only once per week.

What are the implications?

The CPDN work units are big but you get more credit per work unit and you still get the credit frequently because of the use of trickle reporting.

More worrying is that a computation error loses more work. What is the appropriate reaction to this? Complaining is unlikely to be useful as trying to make the workunit smaller has been considered and rejected as not practical. A better reaction would be to decide to make a backup from time to time so if you do suffer an error, you can recover without losing too much work.

1.4 Do I need to be on-line all the time while the software runs?

Absolutely not. Once you have installed the software and registered with the project, you are free to disconnect from the internet.

As your computer reaches trickle points, it will (if set to allow network access) automatically try to “trickle” a small amount of data which is used by the project to track the progress of your experiment. If no network connection is allowed or if it is unable to connect, the trickle will be stored up until the next successful communication. It is not essential to trickle data.

However, an internet connection is required for the final upload of data whenever you finish an experiment. Messages will appear in BOINC giving a large amount of detail about how this upload is progressing. The files are split up into five compressed 'zip' files, and can be incrementally uploaded (i.e. you can pause/resume or exit/resume and so not have to download the entire file if an initial upload was interrupted).

How is that possible? Doesn’t it need to communicate with other computers?

No, your computer is doing a complete model on its own. This is why the work units have to be so big – the communication would have to be far too frequent. You cannot realistically do it even on a network drive let alone over an internet connection.

1.5 Can I suspend the experiment?

The CPDN model should not interfere with the normal use of your computer. Nevertheless, you can suspend all projects via the BOINC Manager’s File Menu. If you just want to suspend one project, that can be done from the projects tab. There is a third possible suspend option on the work tab. Note that this one only suspends the work unit and if you do this it is quite possible a different work unit will (if necessary download and) start.

Alternatively, if you prefer, set your preferences on the CPDN website, where you can choose to only run BOINC applications at certain times of the day or only after a period of inactivity etc.

BOINC does 'task switching' so running multiple BOINC projects allows each application a percentage of CPU time which you can set up for each project, so one project does not use up all the CPU time before finishing a work unit. You can also set projects to exit when preempted, or to remain in virtual memory (so as not to lose any work).

1.6 How do I uninstall the software?

If you wish to stop running CPDN under BOINC, simply 'Detach' from the project. In Windows you can do this by right-clicking on climateprediction.net in the “Projects” tab, and then selecting 'Detach.'

In Linux and OSX open a terminal, navigate to the directory where BOINC is installed and type:

./boinc* -detach http://climateprediction.net.

This should remove all CPDN project files, leaving you free to attach to other BOINC projects.

If you want to uninstall BOINC, you should run the 'Uninstaller' program from Add/Remove Programs in Windows.

For Mac and Linux simply remove your BOINC directory or BOINC executable.

We are grateful for any amount of time/energy you are willing to invest in this exciting project. However, please try to finish your experiment once you have downloaded it – do not download the package just to see what it looks like. This constraint is necessary to preserve the scientific validity of the project as partially completed experiments cannot currently be passed on or evaluated.

2. How To Get Started

2.1 Where should I start?

First of all, please see our Volunteering your computer page. If you have any immediate problems that aren’t covered in this FAQ, you could try searching our participant forum to see if anyone has had this problem before.

2.1.1 Web proxies

If your internet connection uses a web proxy and you use the Windows BOINC graphical client, simply fill in your proxy settings from the 'Settings / Proxy Server' menu selection. If you are running the Linux/Mac BOINC client, you will want to set the HTTP_PROXY environment variable to your proxy server. For other options (i.e. authenticated proxy username/password), please see the BOINC Linux or Mac OS X pages.

2.1.2 Firewall configuration

Note that if you have a firewall you should allow the BOINC client (boincmgr.exe and boinc.exe in Windows; boinc_* in Mac/Linux) to access Internet services on your computer. The client needs to communicate on port 80 (the basic HTTP port used by your web browser). All communication to BOINC servers is initiated by our software as with a web browser – there are no open ports on your computer using this software!

If you are running a firewall make sure that BOINC has full browsing capability on port 80. CPDN Models have been known to crash when a firewall blocks access to a mirror server if it is configured to restrict BOINC access to named servers.

2.1.3 Proxy server and authentication

Win32 :
For Windows, click on 'Setting' in the menu , and then 'Proxy Server' to bring up the Proxy server configuration window.

Mac/Linux :
The Command-Line Version of the BOINC Client Software has optional environment variables and command-line options.

2.2 How do I know when I have got it set up and running properly?

If you can open the BOINC manager, check you have a CPDN task under tasks and it is marked as running.

If the task is suspended rather than running then this may be because you have set BOINC to only run when you are not using the computer. In this case it will work much better if you have selected the option to keep in memory while suspended and you can complete checking that it is working properly by:

1. Leaving your computer on for at least an hour without using it for other intensive work for all that time
2. Then look at the running task in BOINC manager and if the % complete is greater than 0.00% then all is fine.

If you have completed more than 24 hours of processing time on a model check that trickles are reporting.

2.3 Why are some work units only available on one operating system?

As we continue developing new Weather@Home applications – regional climate models that look at particular extreme weather events – we will be moving to a policy of picking a single operating system for each, rather than developing all models for all operating systems. By doing this, we aim to improve both the reliability and the science of CPDN.

Recent new versions of all three operating systems have had backwards compatibility problems which have led to a noticeable decrease in the reliability of the models you have been running for us. By concentrating on a single operating system for each application, we can increase reliability whilst maintaining the current level of effort we’re putting into the development of each application.

Different operating systems produce very slightly different results when running identical models. The differences are really very small, but since we’re often making close call distinctions in very large ensembles of models, these small differences can be significant. If there are different numbers of models run on each operating system within two ensembles that we want to compare – for example, 'natural' and 'anthropogenic' ensembles for weather event attribution studies – this might introduce a subtle bias to our results. We will produce more robust science if all the models in an ensemble are run using the same operating system.

We will endeavour to match the size of the ensemble to the operating system, given there are many more Windows machines running models than either Mac or Linux, but if you have a Mac or Linux machine, please do add it to the project!

We hope this doesn’t cause too much inconvenience, and many thanks again for your support for the project.

3. About the experiment

3.1 What does the CPDN experiment do?

We run large ensembles of climate models to answer questions about how climate change is affecting our world. We run long-term, global experiments looking at climate change into the 21st century and short-term, regional experiments looking at how climate change has altered the risk of extreme weather events.

Find out more about the climate models we run and the climate science behind our experiments.

4. About running CPDN

4.1 How many experiments does the software run?

As many as you let it. The BOINC software runs a climate model which runs all the way through, and then returns a small set of data from the completed model run to us. It then starts another, different model. It goes around this loop until you choose to change to a different BOINC project or uninstall BOINC entirely.

4.2 How much data is sent each way and how frequently?

Downloading the BOINC manager and the model to run are usually the largest downloads. The BOINC manager is around 10MB, or 90MB for the combined BOINC + VirtualBox download.

There are two types of upload:

1. Trickles of typically up to 100KB with frequency in the region of once per 24 hours of processing.
2. Uploads of typically 20MB once per model year processed with frequency in the region of once per 120 hours of processing.

4.3 How much disk space do the models take up?

The biggest model is HadCM3N, which can take up to 2GB per model, immediately before producing a zip file for sending to the project at the 25%, 50%, 75%, and 100% marks. That is, the disk space consumed by the task grows during processing up to about this limit, and then shrinks back down when the zip file is produced, before starting to increase again as processing continues.

Other models are considerably smaller.

4.4 Should I upgrade to BOINC from CP classic?

When the climateprediction.net (CPDN) first launched in 2003, it ran on its own bespoke “classic” software. In 2004, we migrated over to BOINC, so we could share their expertise and software in managing distributed computing projects.

For a while, we ran projects on both the 'classic' software and BOINC, but eventually all our projects were moved over to BOINC.

The 'classic' software is no longer used by CPDN.

5. Problems running CPDN

5.1 Why is there data left on my disk?

When models crash and the model restarts, this can leave data on your computer. In this case, you might need to manually delete data.

5.4 Why won’t it do anything?

This question is a bit general and could be a few things:

• Have you attached to the project? If not see 'Volunteering your computer'.

• Is it struggling to communicate? If so, you may need to change your firewall

• Have you set the preference 'Do work while computer is in use?' to no? If so, the idle detection may be failing. Consider setting 'Do work while computer is in use?' to yes.

5.5 I’m running BOINC, but I’m not getting any tasks

The CPDN project runs several experiments within the main project, each with its own scientific research question. An experiment will be made up of one or more batches of models. These batches are sent out to volunteers as and when the scientists and programmers on the project have them ready.

Given we have a lot of computers attached to the project, they tend to get picked up very quickly.

Unfortunately, the batches are not necessarily sent out very evenly, so sometimes there will be a lot of work units available, and sometimes there won’t.

You can see how many tasks are currently ready to send and how many are currently in progress on the project Server Status page.

If there are no tasks ready to send, please consider attaching your computer to an additional BOINC Project and running tasks for that until more CPDN tasks become available.

6. Performance issues

6.1 Timeslicing between BOINC projects & potential lost work

If you are time slicing make sure you’ve set your preferences to have Leave applications in memory while preempted? set to yes (the BOINC default is no). CPDN checkpoints every 144 timesteps, and if you don’t leave it in memory any calculations you’ve done since the previous checkpoint will have to be redone when CPDN starts up again. If other applications require the memory CPDN may get swapped out, but that’s a much smaller overhead than you’d get if you were preempted at 143 timesteps!

6.2 BOINC GUI display tabs

The Disk and Work tabs do a great deal of communications with the project code. Neither of these should be your normal display tab, even when minimized. A 2 GHz computer can lose 1% of processing keeping these tabs updated. The overhead is much greater for slower computers (a P166 can lose 50% of processing).

7. Questions, problems and discussion forum

You can ask BOINC-specific questions on the CPDN Forum. This forum includes a BOINC-style discussion section.

Please search the forum to see if someone else has already asked your question before posting.

We would like to encourage you to use the forum, where participants can share their views, and perhaps provide advice on some of the common problems. Our team members and many knowledgeable participants regularly read the posted messages, so most of your comments will get attention within a few days.

Alternatively, you can contact us. Comments are read by CPDN staff and by our volunteer moderators.