[CentOS] Ext4 on CentOS 5.5 64bit

Thu Dec 23 15:08:14 UTC 2010
Ross Walker <rswwalker at gmail.com>

On Dec 23, 2010, at 2:12 AM, cpolish at surewest.net wrote:

> Matt wrote:
>> Is ext4 stable on CentOS 5.5 64bit?  I have an email server with a
>> great deal of disk i/o and was wandering if ext4 would be better then
>> ext3 for it?
> Before committing to ext4 on a production server, it
> would be good to consider the comments made in 
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/317781/comments/45
> which presumably still apply to current CentOS 5.5 64-bit kernels.
> As I read it, Ts'o argues that the apparent loss of stability
> compared to ext3 is a design issue in the realm of applications
> that run atop it. I hope this is not a misreading.

Waiting for applications to be properly written, ie use fsync(), is no way to pick a file system. You'd have the same problems on xfs or any other file system that does delayed writes.

It was only a side-effect of ext3's journal=ordered that caused it to flush dirty pages every 5 seconds. If that's what you want then you can use sysctl to tune vm to flush every 5 seconds and that will cover all delayed write file systems.