Stephen Fromm wrote:
> How much memory (RAM) would I need to efficiently run SPM99 on a Pentium
> II/III machine? Someone in this group mentioned 700MB, but from my lab's
> experience this isn't convincing. People here say 1GB is necessary. Is
> this true? And how is performance correlated with amount of RAM you have?
> Finally, what other components besides RAM have a large effect on performance?
>
> Steve Fromm
> NIDCD/NIH
In our experience with SUN, Linux and PC there are three factors that determine
speed in SPM with fMRI data. In order of importance they are RAM, Processor,
HD. We run SPM on a dual processor Sun Ultra 60 with 2GB of RAM and we have
experienced a drastic improvement over our previous 500MB. The idea is to avoid
swapping at all costs. The processor has an obvious impact on performance but
many ignore a common bottleneck in storage. We use Ultra wide LVD SCSI 10,000 RPM
hard drives. We found that due to the large number of files and the size of our
volumes the I/O is also a crucial part of performance.
The bottom line is: be sure that your system is well balanced. Investing large
amounts in one of these three areas while ignoring the others will have minimal
impact. Although, if you can only go for one area, an increase in RAM will almost
always cut your processing time. (this is an oversimplification, there are
situations where an increase in RAM will have no effect on your speed. To get the
full picture you need to take into account your specific studies and paradigms,
file sizes, existing ram, whether you will do group analyses, etc...)
Joseph Grun
Columbia University
College of Physicians and Surgeons
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