commit interval

[Valerie Henson]

On Wed, Feb 20, 2008 at 4:50 AM, Thomas Andrews <tandrews at grok.co.za> wrote:
> Hi,
>
>  I have an ext3 partition on a compact flash device. I was thinking of
>  reducing the commit interval to say 30 sec, but I'm not sure it's really
>  necessary.
>
>  What I'd like to know is if ext3 will *actually* do any writes to the
>  journal if none of the data has changed, and given that it's mounted
>  noatime. eg, if only one file is modified every hour, will the journal
>  still write every 5 seconds?
>
>  I am using ordered mode btw.

It depends on what you are doing to the file system.  Lots of writes?
No writes?  Some writes?  Reducing commit interval will help if you
are doing writes.  The journal only commits if there is some change to
write.  With noatime, file reads will not cause any changes.

Have you considered jffs2?  Sure, CF devices do hardware
wear-leveling, but in my experience they do it extremely badly.  For
flash, ext2 is better than ext3 if you can eat the fsck time.

-VAL