> I'm am trying to run 4 analyses or more at the same time (with 20 subjects
> in a Fixed Effects model, this has proven to be very cpu demanding. I was
> thinking of using an offsite supercomputer and have a couple of questions.
You should find that running one analysis at a time is more efficient (unless you
have several CPUs).
>
> does spm only work with local files ?
It also works with files on NFS mounted disks, but this is a little bit slower.
>
> is spm continuously accessing the img/hdr files throughout the 'estimate
> model' analysis (while reading and masking data) or only during
> 'calculating globals' part?
It constantly keeps reading in new bits of data from the .img files. With lots of subjects,
there are few computers with enough RAM and swap to store all the data in memory at once.
Besides, most architectures only allow either 2 or 4 Gbytes of memory for each Matlab session
(largest signed or unsigned 32 bit integer is either 2.1475e+09 or 4.2950e+09).
Best regards,
-John
--
Dr John Ashburner.
Functional Imaging Lab., 12 Queen Square, London WC1N 3BG, UK.
tel: +44 (0)20 78337491 or +44 (0)20 78373611 x4381
fax: +44 (0)20 78131420 http://www.fil.ion.ucl.ac.uk/~john
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