Peter Kjellstrom wrote: > On Monday 22 January 2007 17:05, Matt wrote: > >> What are advantages of 64 bit OS anyway? I was thinking with i386 the >> max RAM you could have was like 4 gigabyte or something? 64 bit >> allows quite a bit more, right? >> > > You can have alot of RAM even in a 32-bit system. However, there is also the > issue of efficiency and applications being able to actually use alot of > memory. Here are some random bits of information on the subject: > > * you can have alot more than 4G on 32-bit with pae (hugemem kernels) > * ...but, already at ~900M 32-bit has to start using highmem > * ...which can cause problems for (old and badly designed) applications > already at ~900M > * 32-bit EL kernels have 4K kernel stacks, 64-bit has 8K, affects eg. XFS > > >> I am upgrading a very heavilly used email server to a AMD64 dual core >> with CentOS. I am staying with i386 since the web GUI we use lists >> 64bit support as beta and I do not want any problems. >> > > Not a bad choice, software functionality is probably one of the biggest > differences between 32- and 64-bit. > > /Peter > Somebody feel free to slap me upside the head if I'm wrong, but as I understand it, you can utilize up to 16GB on the standard SMP kernel. The bigmem kernel allows up to 64GB, IIRC. I have no idea the RAM limits on the x86_64 kernel. Didn't look. Peter -- Peter Serwe <peter at infostreet dot com> http://www.infostreet.com "The only true sports are bullfighting, mountain climbing and auto racing." -Earnest Hemingway "Because everything else requires only one ball." -Unknown "Do you wanna go fast or suck?" -Mike Kojima "There are two things no man will admit he cannot do well: drive and make love." -Sir Stirling Moss