Date:    Tue, 12 Sep 2000 16:06:47 -1000
To:      Edoardo S Biagioni
From:    Bryan Lee Norman
Subject: ramDisk

i found this how-to...maybe it can give you an idea.

CREATING A RAMDISK
You can create a RAMDISK as large as your available RAM, less the memory
needed for the operating system and applications. If you have 256M of RAM,
a 200Mbyte RAMDISK would allow 56Mbyte of RAM for the applications and
operating system.

1. Edit /etc/lilo.conf.

Add the line: ramdisk=size-in-Kbytes

The sample lilo.conf below creates a 40Mbyte RAMDISK:

boot=/dev/hda
map=/boot/map
install=/boot/boot.b
prompt
timeout=50
image=/boot/vmlinuz-2.0.32
label=linux
root=/dev/hda2
initrd=/boot/initrd-2.0.32.img
ramdisk=40000
read-only
append="mem=252M"

2. Run lilo to recompile the lilo.conf information. (On the command line
type lilo and press Enter.)

3. A RAMDISK can be mounted to any empty directory, or use mkdir to create
a directory mount point.

For example, if you want to have the RAMDISK on a temporary directory in
/home,

cd /home
mkdir temp

4. Edit /etc/rc.d/rc.local so the RAMDISK gets formatted and mounted on
system boot.

Add the following lines to the end of rc.local:

mke2fs -m0 /dev/ram 40000
mount /dev/ram /home/temp 

WHAT THE LINES DO:
"mke2f" assigned the RAMDISK to /dev/ram and formats it with the UNIX
filesystem.

"mount" mounts the RAMDISK /dev/ram on the directory /home/temp. All
subsequent writes or reads to /home/temp will be done on the RAMDISK.

MULTIPLE RAMDISKS
You can add multiple "mke2fs" and "mount" lines to create other RAMDISKs.

For example:

mke2fs -m0 /dev/ram2 100000
mount /dev/ram2 /home/temp2

This creates a 100Mbyte RAMDISK called /dev/ram2, formats it, and mounts
it to the /home/temp2 directory.

5. Load the RAMDISK. Data must be written to the RAMDISK before it may be
read. It is common to back up the RAMDISK on a hard drive and reload the
RAMDISK from the hard drive upon reboot.

For example, this line could be added following the mke2fs/mount lines in
rc.local:

cp /backup/* /home/temp

The "cp" copies all files on the hard disk backup directory to the RAMDISK
mounted at /home/temp.

Similarly, if the information on the RAMDISK is changed during operation,
it must be rewritten to the hard disk backup before rebooting or turning
off power.

6. After editing lilo.conf and rc.local, restart the computer. After
executing LILO and rc.local, your RAMDISK will be operational.

WHERE TO USE RAMDISKS
Use RAMDISKs to replace access to frequently used hard disk files. In the
database world, information access is dramatically accelerated by putting
database indices into RAMDISK. Smaller databases can be entirely contained
in RAMDISK.

Some frequently used operating system files might benefit from being
placed in RAMDISK.

This has been tested on LINUX Red Hat 5.0, 5.2., and 6.0.