John R Pierce
2009-Mar-30 18:24 UTC
[CentOS] How to check server kernel support 32 Gb RAM (X86,
> > > we have CENTOS 4.7 (X86) on DELL server, I already put 32 GB RAM on it. I can use "top" or "free" to check memory and it did show 32 GB. > > I check REDHAT site and found it say: > > The "SMP" kernel supports a maximum of 16GB of main memory. Systems with more than 16GB of main memory use the "Hugemem" kernel. > > I use "uname -r" to check kernel and it show: > > # uname -r > 2.6.9-78.0.13.ELsmp > > It did NOT show "Hugemem", does this server kernel support 32 GB or not? If NOT how can I change kernel to "hugeme"?Dare we ask why this isn't a 64bit server? using 32gb of memory on a processor architecture that can only directly address 4GB at a time is kind of brutal, unless this server is handling a rather large number of connection sessions at the same time. For instance, a 32bit database server will have a max of about 2.5GB of shared memory usable. to install the hugemem kernel, yum install kernel-hugemem reboot, and test this by selecting it in the grub menu, then adjust /boot/grub.conf to suit. read the release notes carefully on hugemem, its a very high overhead thing, as the kernel runs in a private memory space seperate from the applications, so all kernel<->user transfers are complex and slow. http://www.centos.org/docs/4/html/release-notes/as-x86/
mcclnx mcc
2009-Mar-30 18:32 UTC
[CentOS] How to check server kernel support 32 Gb RAM (X86,
The reason we did not use 64 bits O.S. due to we still have some problem run 64 bit ORACLE on X86_64. I have another question: since server we have is "SMP" how come it can show 32 GB RAM on application like "top" and "free"? Thanks. --- 09/3/30 (?)?John R Pierce <pierce at hogranch.com> ???> ???: John R Pierce <pierce at hogranch.com> > ??: Re: [CentOS] How to check server kernel support 32 Gb RAM (X86, > ???: centos at centos.org > ??: 2009 3 30 ? ?? 2:24 > > > > > > we have CENTOS 4.7 (X86) on DELL server, I already put > 32 GB RAM on it.? I can use "top" or "free" to check > memory and it did show 32 GB. > > > > I check REDHAT site and found it say: > > > > The "SMP" kernel supports a maximum of 16GB of main > memory. Systems with more than 16GB of main memory use the > "Hugemem" kernel. > > > > I use "uname -r" to check kernel and it show: > > > > # uname -r > > 2.6.9-78.0.13.ELsmp > > > > It did NOT show "Hugemem", does this server kernel > support 32 GB or not?? If NOT how can I change kernel > to "hugeme"? > > Dare we ask why this isn't a 64bit server?? ? > using 32gb of memory on a processor architecture that can > only directly address 4GB at a time is kind of brutal, > unless this server is handling a rather large number > of connection sessions at the same time.? ? For > instance, a 32bit database server will have a max of about > 2.5GB of shared memory usable. > > to install the hugemem kernel, > ??? yum install kernel-hugemem > reboot, and test this by selecting it in the grub menu, > then adjust /boot/grub.conf to suit. > > read the release notes carefully on hugemem, its a very > high overhead thing, as the kernel runs in a private > memory space seperate from the applications, so all > kernel<->user transfers are complex and slow. > http://www.centos.org/docs/4/html/release-notes/as-x86/ > > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos >______________________________________________________________________________________________________ ?????????Yahoo!??????2.0????????????? http://tw.mg0.mail.yahoo.com/dc/landing