ext2/3/4 group size

Yioryos Asprobounitis mavrothal at yahoo.com
Thu Mar 31 04:17:03 EDT 2011

--- On Thu, 3/31/11, Arnd Bergmann <arnd at arndb.de> wrote:

> From: Arnd Bergmann <arnd at arndb.de>
> Subject: Re: ext2/3/4 group size
> To: devel at lists.laptop.org
> Cc: "Yioryos Asprobounitis" <mavrothal at yahoo.com>
> Date: Thursday, March 31, 2011, 3:34 AM
> On Thursday 31 March 2011 08:45:24
> Yioryos Asprobounitis wrote:
> > 
> > I was wondering if it makes any sense when making an
> ext fs on an SDcard 
> > to try to align the erase block of the card with the
> ext2 group size. 
> > eg assuming a card with a 4KB pages and 4MB erase
> blocks, try something
> > like `mkfs.ext3 -b 4096 -g 1024'
> > Could it offer any speed advantage in garbage
> collection or just tax the
> > file system with the keep-up of 1000 groups (for a 4GB
> card)?
> > (If I got it all wrong, please explain :-)
> In theory, it should help to do this, and I've had the same
> idea. However,
> I haven't seen anyone back it up with numbers, and it may
> as well have
> the opposite effect because of something I haven't thought
> of.
> What kind of card do you use specifically?

I have a very good 2-year old 4GB class 6 Transcend 
a poor 1-year old 4BG class 6 Kingsoton
and  terrible 2-year old 8GB A-data
Rating is based on iozone data and "terrible" means that I get file corruption quite often. Kingston is just slow.
None of them is formatted as suggested.

>     Arnd


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