On Thu, 2007-08-30 at 14:51 -0600, Andreas Dilger wrote:

On Aug 30, 2007  12:12 -0700, Mingming Cao wrote:

quoted

On Thu, 2007-08-30 at 17:37 +0200, Valerie Clement wrote:

quoted

This patch adds a new option -D <descriptor-size> to mkfs to allow creating
ext4 filesystems with larger group descriptor size.

By default, the group descriptor size is 32 bytes.
To support 64-bit physical block numbers and thus to be able to use filesystems
 > 16TB, the group descriptor size must be increased to 64 bytes.

Could you explain a bit more why we need this option? It seems to me we
could make the block group descriptor size to 64bytes whenever creating
a ext4 filesystem by default. Is there any case we need to create ext4
with old 32 bytes block group descriptors?

Because we will only have a single tool "mke2fs", and it should be able
to format filesystems for all kernels.

I agree. I was wondering why not make the 64bytes block group descriptor
for ext4 as default. So by default we don't need to specify the size
when creating ext4 fs.

Also, it may be desirable to
make the descriptor larger for whatever reason (e.g. testing some new
feature).

Okay, that could be useful for ext4. Don't feel ext2/3 needs that
option.

Regards,

Mingming