What's the benefit of placing linux bin etc user on RamDisk?

Question

I found that on my bluehost server, it places "bin", "etc", "usr", and "php" on a 4GB ramdisk. The ramdisk usage was changing very frequent and fast. It seems when I run PHP script, it load the data to this ramdisk, then flush to the disk. But on my own server, when I run the PHP script, it write on the disk. Could you explain how bluehost use this ramdisk for PHP? Thank you.

[~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
rootfs                208G   91G  107G  46% /
fakefs                208G   91G  107G  46% /root
fakefs                1.8T  136G  1.7T   8% /home/user
fakefs                4.0G  297M  3.8G   8% /ramdisk/bin
fakefs                4.0G  297M  3.8G   8% /ramdisk/etc
fakefs                4.0G  297M  3.8G   8% /ramdisk/usr
fakefs                4.0G  297M  3.8G   8% /ramdisk/php
fakefs                208G   91G  107G  46% /var/lib
fakefs                208G   91G  107G  46% /var/lib/mysql
fakefs                208G   91G  107G  46% /var/log
fakefs                208G   91G  107G  46% /var/spool
fakefs                208G   91G  107G  46% /var/run
fakefs                4.0G  401M  3.7G  10% /var/tmp
fakefs                208G   91G  107G  46% /var/cache/man

score 2 · Accepted Answer · edited Sep 28 '13 at 13:29

It looks like your entire drive is in fakefs and thus it makes use of RAM to speed up the use of binaries, scripts, etc.

http://furryterror.org/~zblaxell/projects/fakefs/doc/architecture/node3.html

From the list of features, it says that the fakefs disk access is astonishingly slow.

I do not know enough about the ramdisk to confirm 100% but I would imagine that they resize it depending on how much space they have for other tasks. So if you run a PHP script that makes use of a lot of RAM, it may reduce the size of the ramdisk.

What's the benefit of placing linux bin etc user on RamDisk?

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