change ext3 journal mode to writeback

There are three mode for ext3 journal:
 1) journal
 2) journal ordered
 3) journal writeback

By default, the linux distribution use 'ordered' mode. However it's better to use 'writeback' mode if there are many system disk IO.

Here is the steps:
 1) edit /etc/fstab, append 'data=writeback'. That will be:
LABEL=/   /    ext3    defaults,data=writeback        1 1

 2) edit /boot/grub/menu.lst, append 'rootflags=data=writeback' in boot option. That will be:
kernel /boot/vmlinuz-2.6.18-243.el5 ro root=LABEL=/ ide0=noprobe rhgb quiet rootflags=data=writeback

 3) IMPORTANT:  adjust tunable filesystem parameters.
tune2fs -o journal_data_writeback /dev/hda1

OK, It's done! reboot the system, use this command to check the result:

    dmesg | grep mode



This message should be there:
...
EXT3-fs: mounted filesystem with writeback data mode.
...

or use tune2fs -l /dev/hda1

if step 3 is missing (actually I did go to the wrong way), the root filesystem maybe read-only. you can remount the root filesystme use this commnad:

    mount -n -o remount /

Try Openshift

Openshift is a Redhat's PaaS, which is similar with Google's GAE. It can let user to update APP to cloud without considering maintain the application deploy.

I tried Openshift express verison. It support PHP, Ruby and Python environment. I follow these blog posts:

https://openshift.redhat.com/app/getting_started/express
http://blog.ianweller.org/2011/05/12/openshift-express-first-thoughts/

Two things to mention after using openshift
1. Very quick to deploy your application to cloud, just 3 or 4 commands can work
2, The application source is maintained by git, since git is useful on distributed environment.
user can upload and clone the application source codes just using git