On Thu, 14 Jun 2012, Ted Ts'o wrote:

On Thu, Jun 14, 2012 at 12:14:13PM -0400, Nicolas Pitre wrote:

quoted

Let's not forget that, in almost all cases, filesystem images are not 
created live on the final medium.  Factories are picking a batch of 
flash devices and a pre-built filesystem image is stamped on them, and 
there might not even be a guarantee that those flash devices will all 
have the same characteristics.  So to say that making this tuning at 
mkfs time is probably not the best strategy.

Sure, that just means there needs to be a way of overriding the values
used by mke2fs.  (Because as you create the fs image, the storage
device parameters may make a difference to how blocks get allocated.)

The reason why I talk about making it work automatically at mke2fs
time is that the vast majority of created file systems (where a
specially created fs by a handset vendor counts as "one", even if it
then gets stamped on millions of devices), the end user is someone
naive/oblivious, so the right thing *has* to happen by default in the
common case of running mke2fs on the storage device where the file
system gets used.

Absolutely.  However it is fair to say that less than 0.01% of total end 
users will even think of running mke2fs on their device.  So another 
strategy that can be executed at run time when the fs is live would be 
required too.


Nicolas