Model specification help

Thank you for this. I will return to it tomorrow and let you know how it 
goes. As for the machine it's running on: it's a dual-Xeon 2.8Ghz IBM 
eseries server with 6GB RAM, running debian Linux, kernel 2.6.18.  So the 
3GB per-process memory limit applies. I also have access to a shared server 
with "twenty-four 1.05 GHz Ultra-Sparc III+ processors and 40 GB of main 
memory" running solaris, if that's better.

Andrew,

That gets you onto a 64-bit platform, beyond the 32-bit-Intel 4GB memory (3G 
for user process, 1G for OS kernel) limit, and beyond a bunch of other data 
size limits.  The memory bandwidth available to you on the Solaris machine is 
also likely to be much more significant - something that you will find quite 
pleasant for even some more trivial analyses.  :)

Much better, certainly!  [And very much like what 'beefy' R code is most 
frequently run on...]

W.r.t. the eSeries server you're commonly running on now - if you can have 
your systems people check to make sure that you have a PAE-enabled linux 
kernel running, you might be able to muscle past the 3GB mark with a single R 
process.... with some work.

[If the machine can actually "see" all 6GB of memory, you probably have a PAE 
kernel.]

--e