Trying to move slots dir to /tmp doesn't work


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Questions and Answers : Unix/Linux : Trying to move slots dir to /tmp doesn't work

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Profile Bjorn Munch
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Message 1424507 - Posted: 5 Oct 2013, 8:31:56 UTC

I started running SETI@home on my Linux Mint 14 desktop a week ago. Seeing that the 6 concurrent tasks write to files in the slots directory all the time, I moved the stuff over from the SSD to the hard disk. But then I thought maybe it would be better to have it on /tmp to avoid writing to disk at all during processing.

I first tried the obvious: mv slots to /tmp/BOINC/slots and replace with a softlink. That caused all tasks to crash after restart, and the error is "execve: no such file or directory". Then I tried creating softlinks *back* to the hard disk from /tmp/BOINC/ except for slots and starting the manager from there. Same result, and now it seems my computer is temporarily banned after reporting 40 errors in a row. :-( Luckily I still have 2 tasks left which I can report in 3+ hours and then hopefully I will be allowed some more.

Of course having slots in /tmp means all running tasks are lost if the computer crashes, but that would probably happen anyway. In any case, that happens so rarely it's not a big problem. For a controlled shutdown I could copy over to disk after stopping the tasks.

Is there any way to have slots placed under /tmp short of copying *everything* over to /tmp before starting? And yes my /tmp is on tmpfs so it really is in memory, not on disk. :-)

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Message 1424574 - Posted: 5 Oct 2013, 13:27:11 UTC - in response to Message 1424507.

The BOINC client binary makes these slots directories and copies the science application binary and task files from the /boinc/projects/setiathome.berkeley.edu/ directory to the correct slots/x directory, keeping track of where it put what. When the science application is done, the BOINC binary moves the data back to the /projects/* directory, deletes the slot directory and everything in it, then makes a completely new slot directory and copies the next binary + data files there.

That's why your softlinks don't work, the client doesn't work with those.
So your only option is to uninstall BOINC and reinstall it completely to where you want it to run from.
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Jord

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Message 1424578 - Posted: 5 Oct 2013, 13:55:15 UTC - in response to Message 1424574.

Well, a softlink named slots should normally have worked but I guess the system makes some assumptions about relative paths which are not correct with that setup.

I had no trouble moving from the SSD to the harddisk. I suspended running tasks, moved everything over, edited a few files then started up again.

I could probably copy everything to /tmp/BOINC and run some hourly cron job to rsync stuff back to disk. But I'll let it run as is for now. I joined rosetta@home too so that my CPU can do something useful while waiting for SETI to accept me back. :-)

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Message 1425012 - Posted: 6 Oct 2013, 20:38:14 UTC - in response to Message 1424578.

And that's exaclty what I did: copied everything over to /tmp/BOINC, corrected the path in the startup script and now it's churning along happily. I sync back to disk *except* the slots directory once every hour. Saves the disk from having to work 24/7 and it might speed things up slightly too. I have 16 Gb memory so no danger of running out of space on /tmp :-)

Questions and Answers : Unix/Linux : Trying to move slots dir to /tmp doesn't work

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