[RESOLVED]Very slow write-speed on microSD (GuruServer+)

[Mimoza]

I recently buy a microSD card (Dan-Elec 8Go class4), and i test his performences in read/write;
So i follow this page for testing

Read

Code:

sheevaplug-debian:/media# dd if=/media/usb0/test.tst of=/dev/null
1024000+0 records in
1024000+0 records out
524288000 bytes (524 MB) copied, 25.5926 s, 20.5 MB/s

Well, for read speed it's Ok

Write

Code:

sheevaplug-debian:/media# dd bs=1024 count=50K if=/dev/zero of=/media/usb0/test.tst
^C
8173+0 records in
8173+0 records out
8369152 bytes (8.4 MB) copied, 924.167 s, 9.1 kB/s

But for write speed 

I test with another one microSD card (512Mo) and for the write-speed i have the same problem  (for read it was Ok)

So i do the same test with a card reader on my computer and i find more than 7Mo/s write speed (nearly the same read speed)

So wat's wrong with my plug 
I don't flash  U-Boot and Kernel, both are originals.
I will be obliged to upgrade U-Boot/Kernel ?

For information my plug is very hot (230v~) but don't reboot, and when get out the card she is very hot too 

Any suggestion ? idea ? same experience ?

For comparaison can you do the test ?

[mabe42]

Hi Mimoza,

I had similar problems. Also 230V version, original u-boot and kernel. My write speed was about 100-150kB/s on a class 6 card.

When I wanted to try if it was the card or the guru, I plugged the card into different readers at various computers. However, I could not read it. I finally reformatted it. Now it's ext3. The write speed is in the range of some MB/s. I don't remember the exact value. Read speed is also ok. And I can read/write it with any other reader/computer combination that can handle ext3.

Regards,

Matthias.

[Mimoza]

My card was formated in ext3 by a debian distro on my PC
Well, i'll format again my card but with my plug this time ...

Thanks for your reply

[Mimoza]

I follow instruction here and ....

Code:

sheevaplug-debian:~# dd bs=1024 count=200K if=/dev/zero of=/mnt/sdcard/test.tst
204800+0 records in
204800+0 records out
209715200 bytes (210 MB) copied, 24.6595 s, 8.5 MB/s
sheevaplug-debian:~# dd if=/mnt/sdcard/test.tst of=/dev/null
409600+0 records in
409600+0 records out
209715200 bytes (210 MB) copied, 2.03942 s, 103 MB/s

Well after re-formate my sdcard WITH THE PLUG performance are quite good 

But it's really strange, why if the sdcard is formated from other pc performance are so bad 

[Mimoza]

Humm finally the problem is really strange ...
I test again the sdcard after normal shutdown/ restart of plug and the problem reappear   
but with a umount / mount it's works fine again 

i don't understand ... 

edit :
Finally when i mount manually the sd card by a
mount /dev/sdb1 /media/usb0
It works fine
But when the system automount the sd card i find again my poor write speed 
I create a new topic for the probleme

[pietsnot]

because of the used blocksize:
your first dd uses blocksize 1024
your 2nd dd uses blocksize 512 (implicit)