Which microSD card does sped matter?

classic Classic list List threaded Threaded
7 messages Options
Reply | Threaded
Open this post in threaded view
|

Which microSD card does sped matter?

Joop Boonen
I have a question. I've ordered a Freerunner it should arrive within 2 weeks.

I'm thinking of buying an extra bigger (8GB) microSD card. I see that
microSD has different classes i.e. speeds. Does the Freerunner benefit
from the speed if so how much?

What is the best speed for the Freerunner to buy?

Regards,

Joop.


_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware
Reply | Threaded
Open this post in threaded view
|

Re: Which microSD card does sped matter?

Al Johnson-3
Joop Boonen wrote:
> I have a question. I've ordered a Freerunner it should arrive within 2 weeks.
>
> I'm thinking of buying an extra bigger (8GB) microSD card. I see that
> microSD has different classes i.e. speeds. Does the Freerunner benefit
> from the speed if so how much?
>
> What is the best speed for the Freerunner to buy?

IIRC the maximum transfer rate from the card is slower than Class 2, so
you won't see any benefit from faster cards in the Freerunner.

_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware
Reply | Threaded
Open this post in threaded view
|

Re: Which microSD card does sped matter?

Esben Stien
Alastair Johnson <[hidden email]> writes:

> the maximum transfer rate from the card is slower than Class 2, so
> you won't see any benefit from faster cards

Capacity and latency are two very different things. You're mixing the
two badly up in this sentence;).

--
Esben Stien is b0ef@e     s      a            
         http://www. s     t    n m
          irc://irc.  b  -  i  .   e/%23contact
           sip:b0ef@   e     e
           jid:b0ef@    n     n

_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware
Reply | Threaded
Open this post in threaded view
|

Re: Which microSD card does speed matter?

Joop Boonen
In reply to this post by Al Johnson-3
> Joop Boonen wrote:
>> I have a question. I've ordered a Freerunner it should arrive within 2
>> weeks.
>>
>> I'm thinking of buying an extra bigger (8GB) microSD card. I see that
>> microSD has different classes i.e. speeds. Does the Freerunner benefit
>> from the speed if so how much?
>>
>> What is the best speed for the Freerunner to buy?
>
> IIRC the maximum transfer rate from the card is slower than Class 2, so
> you won't see any benefit from faster cards in the Freerunner.
>
> _______________________________________________
> hardware mailing list
> [hidden email]
> http://lists.openmoko.org/mailman/listinfo/hardware
>

Yesterday I bought a SanDisk Mobile Ultra  microSD 4GB class 6 it seems as
it was cheaper with an usb adaptor than a slower class2 version.

I have a feeling that the boot processes if much faster than the boot
process with the supplied class 2 card.

Regards,

Joop.


_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware
Reply | Threaded
Open this post in threaded view
|

Re: Which microSD card does speed matter?

Mike Westerhof (mwester)
Joop Boonen wrote:
> Yesterday I bought a SanDisk Mobile Ultra  microSD 4GB class 6 it seems as
> it was cheaper with an usb adaptor than a slower class2 version.
>
> I have a feeling that the boot processes if much faster than the boot
> process with the supplied class 2 card.

There are multiple timing factors to consider, and the generic class
designation is really just "marketing-speak".  The transfer rate that we
can get on the GTA02 is limited, and will be far less than the 25MHz max
clock frequency (the same is true on the GTA01, although for different
reasons).  The kernel will tell you what speed it selected for the card
at boot time.  But that's just the speed at which the data is clocked in
once its ready.

The other factor is how long it takes from issuing the command to the
card to fetch a block of data until that data is ready to be transferred
in (latency).  Nothing currently collects and displays this bit of data
for the user, but it would be a very important factor in overall
performance, and it seems logical that higher-quality, higher-speed
cards should have better specs here.

It would be neat if someone could work up a patch to collect and display
a min/max and running average of the latency time as observed by the
kernel, but in reality I think that a quick test with bonnie++ on the SD
filesystem will provide a much truer picture of how the various cards
perform on the various devices.  Maybe someone should add such a page to
the wiki for users to submit their test results with various brand cards?

Mike (mwester)

_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware
Reply | Threaded
Open this post in threaded view
|

Re: Which microSD card does sped matter?

Flemming Richter Mikkelsen
In reply to this post by Esben Stien
On Tue, Nov 18, 2008 at 19:13, Esben Stien <[hidden email]> wrote:
> Alastair Johnson <[hidden email]> writes:
>
>> the maximum transfer rate from the card is slower than Class 2, so
>> you won't see any benefit from faster cards
>
> Capacity and latency are two very different things. You're mixing the
> two badly up in this sentence;).
>

Capacity is the size:p
I assume you meant transfer rate and latency

_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware
Reply | Threaded
Open this post in threaded view
|

Re: Which microSD card does sped matter?

Angus Ainslie
In reply to this post by Joop Boonen
On Tue, Nov 18, 2008 at 12:47 AM, Joop Boonen <[hidden email]> wrote:
> I have a question. I've ordered a Freerunner it should arrive within 2 weeks.
>
> I'm thinking of buying an extra bigger (8GB) microSD card. I see that
> microSD has different classes i.e. speeds. Does the Freerunner benefit
> from the speed if so how much?
>
> What is the best speed for the Freerunner to buy?
>

I've tried a few different cards and it seems the faster ones are more
likely to corrupt the card or not be recognized at all. I don't think
any of the class 2 cards I've used have failed. I haven't done any
hard tests to verify this so the evidence is purely anecdotal.

Angus

--
Angus Ainslie
http://www.handheldshell.com/

_______________________________________________
hardware mailing list
[hidden email]
http://lists.openmoko.org/mailman/listinfo/hardware