no disk space

Point taken!

To all people having problems with disk space:

There are three key preference settings about this which you should check through the "View or edit general preferences" link on your account page on the project website. If you are attached to multiple projects, you can make changes on any of the project websites and over time those changes will appear on all websites through which you have an active project. You have to "Update" changes on the website (otherwise they wont "stick") and you have to "Update" your own BOINC client, otherwise the change will be delayed until the next server/client communication. Please note that you cannot ultimately have different general preferences for things like disk space on the different projects to which your computer is attached unless you start using the various "venue" options of home, work, school, but that is beyond the intended scope of this discussion. The final point to fully understand is that the most recent change on any of the attached project websites will be the one that dominates.

The three key disk preference settings are:-

• * Use no more than XX GB disk space.
  This is an absolute limit and NOT an invitation for BOINC to overuse. If BOINC needs to use 100MB then that's exactly what it will use, irrespective of whether or not you give it permission to use a whole lot more. It is entirely safe to set it to 10GB or even 100GB even if you only have a 2GB disk, as I have in one particular case. BOINC is always limited to the physical size of the partition on which it is installed anyway.

So why do I choose to set mine to 10GB? Simply because, at some time in the future, I may well choose to go beserk and start supporting every single project out there. I don't want to have to remember that I set this puny limit of say 0.5GB because that's all I had available at the time. I'm confident that BOINC is not going to abuse my disk space so why set some restrictively low limit. Can you think of any other major software package (take MS Office for example) that actually gives you a choice to limit its disk usage?

So, unless you have a very good reason to do otherwise, I suggest that you are less likely to ever shoot yourself in the foot by setting this value to something large enough for possible future expansion.

* Leave at least XX GB disk space free. This is also an absolute limit. I make the same point again. What other software package actually offers you the choice of having the software cease and desist if the disk space starts getting a little on the low side? Usually this is an OS function. The OS starts getting stroppy if you look like consuming all the available free space. So once again, since BOINC really isn't going to consume more than it really needs anyway, just set this to a fairly minimal value like 0.1GB or even less if you don't have much free space anyway.

* Use no more than XX% of total disk space. This one is the killer and is not well understood at all, including by me. We really need someone familiar with the code to come forward and really set out exactly what this does. I can't give you a precise answer but I can tell you the results of a few experiments I conducted about 6 months ago when I had a machine that was actually successfully completing work but getting "Client errors" because of disk space issues.

Firstly let me tell you what I *think* it means. Since BOINC is only ever interested in the partition on which it is installed, "total disk space" refers to the size of that partition, and may well be less that the size of the physical disk. So when you have say a 4GB partition and the default is 50% you may well think that this preference is saying that BOINC has permission to use up to 50% (ie 2GB) on this 4GB partition. I am reasonably convinced that this is NOT what will happen.

I believe that the preference is saying that BOINC plus anything else is only allowed to consume up to 2GB and that BOINC therefore cannot proceed unless there is still 2GB free.

Others have suggested that "total disk space" might refer to total free disk space at the time BOINC is installed. So, as an example, again consider our 4GB partition that has say 3GB free when we go to install BOINC. A preference of 50% could therefore mean that BOINC could be limited to 1.5GB. However, once again, I believe it is the reverse to this that is important. I believe the preference is effectively saying that BOINC cannot proceed unless there is still 1.5GB free.

Now I don't really know whether the preference setting (eg 50%) is referring to "total disk space" or "total free disk space", because with many of my systems I've been installing in a clean partition anyway and therefore the two are the same thing. However I am reasonably convinced that we should not be looking at the disk space that is used up but rather we should consider the free space left. If we set that preference to 50% then the balance (also 50%) must remain free or else BOINC will refuse to work. That means that anyone installing in a 20GB partition must leave 10GB free (for a preference setting of 50%) at all times. So, if other things start filling up that free space, BOINC, for no apparent reason might suddenly stop working. I think it is simply this that causes most people to start having problems. They have that preference set too low and are not aware of other things that are gradually consuming disk space. If we are prepared for BOINC to work with an absolute value of 0.1GB, we should set the requirement for the % of the total disk that can be used to a very high value - say 90 - 95%. That way we are only forcing BOINC to keep 5 - 10% free.

Now for the actual example that happened to me 6 months ago. I had a machine whose C:\\ partition where BOINC was installed had a total size of 3.2GB The free space was just over 1.3GB if I remember correctly. The three preferences that I had set were 10GB for max size, 0.2GB for Min Free and 60% of total disk. At the time, my belief was that 60% meant that BOINC could use 0.6 X 3.2 = 1.92GB. I soon started having occasional disk write problems so I changed the 60% to 70%. This cured the problems and I thought no more about it until a few weeks later when the problems started coming back. It wasn't until I noticed that other things had been using up the disk and whilst BOINC was still the same, the free space was now less than 1GB.

The machine didn't belong to me and was being used for other purposes so I wasn't able to really play around with it too much. However I felt it was too much of a coincidence that the problems started firstly when the free space dropped below 1.3 GB = 40% (pref @ 60%) and secondly when it dropped below 1.0 GB = 30% (pref @ 70%). I've since upped the pref to an even larger value and had no further problem.

Of course, all this might be pure coincidence and since I really wasn't able to investigate thoroughly, and didn't keep accurate notes, my memory might be a bit faulty anyway. It would be very illuminating to hear from someone who is familiar with the code. With the current problems, I don't think there is any disk corruption or faulty .xml files. I would be really interested to know if the problems disappear with pref settings of 10GB, 0.1GB and 90% respectively.

So, could all people actually having disk space related problems please set that third preference in particular to say 90 - 95% and see if the problems cease, thanks.

You are having trouble seeing the connection because there is none :). I believe that it was pure chance that the reloading of unchanged preferences seemed to cure (temporarily) the problem. Imagine the following scenario:-

Let's say the preference is to allow BOINC to use 60% of the total disk space and that space is 1.0GB. BOINC cannot work unless 0.4GB is free. Let's say that the current free space is 0.41GB. If no other process is creating temp files then everything continues on happily.

At one point, without user intervention, the user's computer decides to automatically download and install a "critical" update from Microsoft, or perhaps one of a myriad other addon components decides it's time for a new version. I'm just using these things as examples of what could happen. At the height of this updating or upgrading, 20MB of temp files are created and the free space is now only 0.39GB. Is the BOINC client going to have a problem? Well no, probably not as long as the temp files have been deleted and the free space is back to 0.41GB before the server needs to check things out.

Please bear in mind that it's the server that is making the decision that the client machine doesn't have enough free space, and not the client. The client tells the server what the situation is when the client is asking the server for more work and the server wants to do a check. I believe this is why you can get these apparently random, "Now it's OK" and a little later "Now it's not OK" type of events. I've actually seen this happen and been extremely puzzled about how it can flip from "OK" one minute to "Not OK" some time later when BOINC hasn't done anything. The above is my rationalization of the behaviour.

Yes, anything, BOINC, science app or totally unrelated app that is using temp space at just the "wrong" moment could trigger a problem that then just as suddenly seems to go away. It actually can't quite be as simple as I've rationalized it because one of the problems was the science app failing to write out the final answers because of disk shortage right at the end. The local client must be doing a check at that time too.

Yes, yes, yes - it's happened to me and it really throws you into a loop - it's sooooo frustrating. Now I don't really know that I'm right but once I made the changes I suggested, it has not happened again to me in nearly six months now.

I haven't been back to look at Guido's case yet so I will shortly.

I don't think I've caught up with what Bill has to say yet so I'll seek it out too.

Thanks very much for your interest. I'm not sure I have the full story yet but it's one of those things that's been around for quite a while and I've not seen anyone come up with a really complete explanation. I actually did a search on the Seti boards for "disk preferences" and came up with a staggering number of hits where people were reporting this same error. The complaint was basically that "BOINC says I don't have enough disk space but I've got an XXGB disk and there is more than YYGB free - WTF!!!!" People just don't realise that 50% of an XXGB disk is a *lot* of space that BOINC must see as being free. That's not even counting the cases where BOINC is in quite a small partition with little free space on an otherwise reasonably empty, large physical disk.

Nevermind, I see you have already provided an excellent example of what to ask for in Message 21578 on Message boards : Problems and Bug Reports : Disk Space.

Try this again, Gary. Here's a nice example. :)

If not changed and left to its own devices, BOINC will always try to take 100GB. Yes, there are drives bigger than that already. :)