Storing temporary files in a RAM file system.
Using a flash based file system instead of a ramdisk is a good way to- save RAM
- increase the size of the root file system
- preserve file changes after a reboot
Given these benefits, it is still desirable to put some files in a RAM based file system to- allow memory mapped files to be used
- avoid flash write cycles for files that do not need to be preserved
- allow files to be created and written when using a read-only root file systems.
Temporary files are an obvious example. This commandmount -t ramfs ramfs /tmp -o size=4m
mounts a RAM file system on /tmp and limits it to 4 MB. (Leaving off '-o size=4m' will let it grow as long as there is RAM available.)
To mount /tmp during initialization, modify /etc/fstab and one of the system start up scripts in the flash file system. In /etc/fstab, add a line like this:ramfs /tmp ramfs size=4m 0 0
Then add a line in /etc/inittab or /etc/rc.d/rc.sysinit to mount the RAM file system:mount /tmp
Now when the system starts, /tmp files will exist in RAM instead of in on-board flash memory.
If the contents of /var do not need to be preserved between reboots, they can be moved to the RAM file system, too. Using an existing /var as a template, follow these steps:
Create an archive of /var and store it in the flash file system like this:cd /var
tar cf /var.tar .
You may want to empty the log files and remove unneeded files before performing this step.
Then create a script that copies the contents of the archive to /var:mkdir /tmp/var
cd /var
tar xf /var.tar
Next, edit /etc/inittab or /etc/rc.d/rc.sysinit to call the script after /tmp has been mounted.
Replace the /var directory with a link to the one in the RAM file system:rm -rf /var
ln -s /tmp/var /var
Now when the system starts, a var directory is created under /tmp and /var links to /tmp/var. Since the RAM file system is mounted on /tmp, var files are stored in RAM instead of in on-board flash.
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Storing temporary files in a RAM file system.
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Posted - 08 Oct 2003 : 15:19:49
