Re: Swap & RAM on RH 7.3

[Rick Stevens <rstevens vitalstream com>]

Anurag Gupta wrote:
> Hi All,
>
> I have a system with 8GB RAM & RH 7.3(IA32 - Dual CPU
> Xeon).
>
> How can i configure 7.3 to use max RAM & whats the
> limit.

The kernel limit is 64GB.  Just make sure you install the "bigmem"
kernel (bigmem = kernel configged for 8-64GB and SMP).

> Also how can i configure swap space.

The normal setting for swap is 2x your RAM space, however that is just
a suggestion.  A swap partition in Linux can be no larger than 2GB, so
you'd need to set up four separate swap partitions to give you an 8GB
swap, eight if you want to follow the 2x RAM size rule.  For swap
partitions, the easiest way is to create them when you install Linux
and partition the drive.  The installer will create the partitions,
set them up and add them to /etc/fstab so the next boot will activate
them.

If you decide to do it later, you'll need to shrink existing partitions
(using parted--not a trivial task) to make room for them, then create
the partitions using fdisk.  Next, set them up using mkswap:

	# mkswap /dev/hda9

To activate them:

	# swapon /dev/hda9

Add entries to /etc/fstab so it gets used on the next boot:

	/dev/hda9      swap      swap    defaults        0 0

(the system does a "swapon -a" at boot time to activate all partitions
or swap files listed in /etc/fstab).

You CAN create swap _files_ rather than partitions, should you wish to.
The file MUST be contiguous, so you have to create it using dd.  For
example, to create a 2GB swap file:

	# dd if=/dev/zero of=/name/of/swapfile bs=1024 count=2097152
	# mkswap /name/of/swapfile
	# swapon /name/of/swapfile

Don't forget to add entries to /etc/fstab for the new swap file:

	/name/of/swapfile      swap      swap    defaults        0 0

----------------------------------------------------------------------
- Rick Stevens, Senior Systems Engineer     rstevens vitalstream com -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-      "Microsoft is a cross between The Borg and the Ferengi.       -
-  Unfortunately they use Borg to do their marketing and Ferengi to  -
-               do their programming."  -- Simon Slavin              -
----------------------------------------------------------------------