Ext3 users - Sep 2002 - ext3 fs: no userspace writes == no disk writes ?

Hello,

I have a question about ext3 write activity.

I am considering using an ext3 fs on a CompactFlash disk for my
data-logging application (power can disapear anytime).
The quantity & frequency of the data logged itself is not a
problem at all considering flash wear.

But I'm a bit worried about the kernel/ext3 doing regular writes
by itself even when there are no userspace writes.  (worries are
partially caused by memories from long time ago about idle laptop
doing regular writes on disk).

Anybody out there who knows how this works ?

Can I use an ext3 fs without having regular "automatic" writes to
the device it is located on ?  (and thus not destroy my CompactFlash
devices !)

	greetings,
	Rob van Nieuwkerk


PS1: of course nothing from userspace should write frequently to
    the fs, and if there is regular read-activity the fs should
    be mounted with "noatime")

PS2: yes, I know that jffs exists

Hi,

On Fri, Sep 20, 2002 at 01:53:51AM +0200, Rob van Nieuwkerk wrote:
 
> But I'm a bit worried about the kernel/ext3 doing regular writes
> by itself even when there are no userspace writes.  (worries are
> partially caused by memories from long time ago about idle laptop
> doing regular writes on disk).
> 
> Anybody out there who knows how this works ?
> 
> Can I use an ext3 fs without having regular "automatic" writes to
> the device it is located on ?  (and thus not destroy my CompactFlash
> devices !)
There should never be automatic writes (if you see any, tell me, it's
a bug!)  But there are frequently writes that come from unexpected
sources that can trip you up.  A common example is "atime" timestamp
updates, which cause a write even when you just read from a file.
Mounting the filesystem with the noatime option can avoid that.

Cheers,
 Stephen

> But I'm a bit worried about the kernel/ext3 doing regular writes
> by itself even when there are no userspace writes.  (worries are
> partially caused by memories from long time ago about idle laptop
> doing regular writes on disk).
I thought the same, it don't blame to ext3:
http://bulmalug.net/body.phtml?nIdNoticia=1511


-- 
  ricardo galli       GPG id C8114D34
       A paperless office has about as much a chance as a paperless bathroom

> But I'm a bit worried about the kernel/ext3 doing regular writes
> by itself even when there are no userspace writes.  (worries are
> partially caused by memories from long time ago about idle laptop
> doing regular writes on disk).
I thought the same, don't blame to ext3:

http://bulmalug.net/body.phtml?nIdNoticia=1511


-- 
The nicest thing about the Alto is that it doesn't run faster at night.