So Mike, let me ask you a question. If R runs out of RAM, does it begin to use virtual RAM, and hence begin to swap from the hard drive? If so, I could see how a faster hard drive would speed R up when you don't have enough RAM...
On 6/20/07, Mike Prager <[EMAIL PROTECTED]> wrote: > "Matthew Keller" <[EMAIL PROTECTED]> wrote: > > > Robert, > ... > > As for Mike Prager's point about the type of hard drive being > > important, I'm not sure this is right (someone correct me if I'm > > misunderstanding). R stores and accesses objects through RAM - they > > aren't stored and accessed on the hard drive except when reading and > > writing. So hard drive type probably won't make much difference to > > speed in R. > > In my experience, it makes a substantial difference if any > swapping to disk is going on. That will happen if, e.g., other > processes or Windows itself need RAM. Though R keeps the data in > RAM, under Windows, non-SCSI disk I/O puts a noticeable load on > the CPU. As SCSI controllers have CPUs of their own, they > offload much of that work from the system CPU. > > I have compared dual-processor computers with equal RAM, one > with a SCSI subsystem and one with fast (7200 RPM) ATA disks and > slightly faster CPUs. One was my work machine, one my home. The > difference was not subtle. For another example, think of how > slow laptops seem when multitasking, compared to a good > workstation. It is usually the poor disk subsystem that's the > bottleneck, not the CPU. > > Mike > > -- > Mike Prager, NOAA, Beaufort, NC > * Opinions expressed are personal and not represented otherwise. > * Any use of tradenames does not constitute a NOAA endorsement. > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- Matthew C Keller Postdoctoral Fellow Virginia Institute for Psychiatric and Behavioral Genetics ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
