[Sugar-devel] SoaS won't boot XO-1s?

Martin Dengler martin at martindengler.com
Fri Mar 27 11:49:35 EDT 2009

On Fri, Mar 27, 2009 at 04:35:20PM +0100, Elena of Valhalla wrote:
> 2009/3/27 Martin Dengler <martin at martindengler.com>:
> > It's a lot better not to re-format *at all* USB sticks one gets if one
> > can help it:
> >
> > http://wiki.laptop.org/go/How_to_Damage_a_FLASH_Storage_Device
> > http://thunk.org/tytso/blog/2009/02/20/aligning-filesystems-to-an-ssds-erase-block-size/
> actually, the issues in these links seems to be mostly with
> partitioning rather than plain formatting

They are certainly related, to the extent that re-partitioning usually
implied re-formatting.  But I took away a clear message that
formatting is tricky in and of itself:

"To damage such a device, all you have to do is reformat it with any
of the usual Linux-based tools like fdisk, mkfs, and dd."

"...if the filesystem layout is bad, every cluster write might "split"
two pages, forcing the FTL to perform four internal I/O operations
instead of one."

http://wiki.laptop.org/go/How_to_Damage_a_FLASH_Storage_Device, and:

"Aligning your file system on an erase block boundary is critical on
first generation SSD"

...from http://thunk.org/tytso/blog/2009/02/20/aligning-filesystems-to-an-ssds-erase-block-size/

> under e.g. linux a simple
> mkfs.vfat /dev/sdb1
> shouldn't be more problematic than simply writing the same (small
> AFAIK) amount of data.

"Your second set of opportunities to mess up comes when you use "mkfs"
to create the filesystem."

It is significiantly more problematic according to those sources.

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