Any restrictions or recommendations regarding SD cards?

Arnd Bergmann arnd at
Thu Mar 24 17:36:41 EDT 2011

On Thursday 24 March 2011 20:26:05 Christoph Derndorfer wrote:
> Hi all,
> the folks from the Austrian pilot project want to equip the XO-1s there with
> SD cards. Are there any restrictions wrt size, speed, etc. that they should
> be aware of when purchasing the SD cards? I'm particularly asking after
> reading James' mention of seeing more issues with newer cards and the XO-1
> power off bug.
> Or asked the other way 'round: Are there any particular cards or
> manufacturers which people can recommend?

Have a look at my list at

Stay away from brands that typically have only one writable allocation
unit, these will be slow and wear out very quickly when formatted with ext3
or other Linux file systems. Higher is better here, and it's something that
is usually not reflected in the speed class rating. Also avoid those that only
support linear I/O.

Sandisk cards tend to be ok (especially the Ultra and Extreme versions),
Kingston tends to be really bad, most others have somewhat mixed results
though sometimes the cheapest ones can be really good.

Class 10 cards are not required to support efficient random I/O, so they are
sometimes slower than Class 6 cards from the same manufacturer.

If you buy a sample, I'll gladly help you figure out if it's any good before
you buy a lot of them, in return for more data for my survey page ;-).


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