Changing default root filesystem to ext4

[Yasushi SHOJI]

At Wed, 17 Aug 2011 13:11:51 +0200,
Arnd Bergmann wrote:
> 
> On Wednesday 17 August 2011, James Tunnicliffe wrote:
> > One thing I noticed during Ubuntu boot on my Panda was that the mount
> > process would say that it detected btrfs was running on a flash card
> > and it had enabled flash mode. I don't know what is different in flash
> > mode and I don't know if when I let Ubuntu auto-mount a flash card for
> > testing on my Laptop if it enabled it. The only mount option I can
> > find that sounds right is "ssd", which isn't on when I just tested it
> > now.
> 
> Good point. Tixy, do you know what mode you were testing btrfs with?
> 
> btrfs understands the 'ssd', 'ssd_spread' and 'nossd' mount options that
> should have a significant impact here, although it's not clear which of
> these is best for a flash memory card, since the characteristics of
> SD cards are very different from SSD.
> 
> The version of btrfs that I'm looking at does not have any optimization
> for cheap flash drives, only for SSD.

does anyone checked on seekwatcher[1], a visualizing tool Chris Mason
has wrote.  I'm pretty sure that Chris would like to hear what went
good and bad for btrfs as an embedded system's root file system.

[1]:http://oss.oracle.com/~mason/seekwatcher/

just my 2 cents.
-- 
              yashi