ramdisk question

[tckotb]

Is there a simple and safe way to:
-mount a ramdisk at boot
-copy over files from a folder on a hard drive to the ramdisk
-execute a shell script on the ramdisk

then upon shutdown recopy the ramdisk back to the hard drive

[tgalati4]

I run firefox from a ramdisk using these scripts:

tmpfs_firefox.sh:
----------------

#!/bin/bash
# Created 31 Jul 09
# Change this to match your correct profile--firefox's cache directory
PROFILE="4n0pfp5v.default"

cd "${HOME}/.mozilla/firefox"

if test -z "$(mount | grep -F "${HOME}/.mozilla/firefox/${PROFILE}" )"
then
mount "${HOME}/.mozilla/firefox/${PROFILE}"
fi

if test -f "${PROFILE}/.unpacked"
then
rsync -av --delete --exclude .unpacked ./"$PROFILE"/ ./profile/
else
rsync -av ./profile/ ./"$PROFILE"/
touch "${PROFILE}/.unpacked"
fi

exit

--------------------

Put this in your /etc/fstab:


# Added 31 Jul 09 to improve firefox speed using ramdisk
firefox /home/tgalati4/.mozilla/firefox/4n0pfp5v.default tmpfs size=128M,noauto,user,exec,uid=1000,gid=1000 0 0

-----------

This mounts a directory called 4n0pfp5v.default (firefox's cache directory) to a temporary filesystem (RAMdisk) of 128 MB.

-----------

Run firefox using a script that I call firefast located in /usr/local/bin

tgalati4@tpad-Gloria7 ~/Projects/scripts $ cat /usr/local/bin/firefast


#!/bin/bash
# Created 31 Jul 09 to speed up firefox
~/tmpfs_firefox.sh
firefox &
exit

----------------

Check to see if the RAMdisk exists:

tgalati4@tpad-Gloria7 ~ $ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 39G 25G 12G 69% /
tmpfs 944M 0 944M 0% /lib/init/rw
varrun 944M 388K 944M 1% /var/run
varlock 944M 0 944M 0% /var/lock
udev 944M 152K 944M 1% /dev
tmpfs 944M 2.5M 942M 1% /dev/shm
firefox 128M 74M 55M 58% /home/tgalati4/.mozilla/firefox/4n0pfp5v.default

----------------------

An important part: using cron to resync the disk cache with the RAMdisk every 10 minutes.

crontab -e

# m h dom mon dow command
*/10 * * * * $HOME/tmpfs_firefox.sh


So although this does not do specifically what you want, it has worked for me over 2 years. So you can modify the scripts to do something similar.

[papibe]

Ubuntu by default has a ramdisk mounted on /dev/shm

Check if yours is mounted like this:

$ df -Th /dev/shm/

The output should be something like this:

Filesystem    Type    Size  Used Avail Use% Mounted on
none         tmpfs    2.0G  272K  2.0G   1% /dev/shm

Since it's mounted and ready to use, you could start testing your scripts on that partition.

If you need a custom ramdisk (for example a smaller one), you could create one doing this:

mkdir /tmp/myramdisk
sudo mount -t tmpfs -o size=512M tmpfs /tmp/myramdisk/

Hope it helps,
Regards.

[SlugSlug]

just as a side note to this I mounted my /tmp in a tmpfs via fstab and experienced random system crashes (complete freeze up)

[dabbi2000]

since Ubuntu already has the dev/shm, can I then mount /tmp to this target? I don't really see why we need a special tmpfs disk in fstab if Ubuntu has a ramdisk by default?