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Re: pb with sheeva plug and usb/sd memory cards



Hello all,

Today, I got my ssd disk (Crucial 32 Gb "old" sata 3Gb/s) with USB box.
As expected, my pbx running with my SD card could not be stopped (lots of "error -110" -- problems with the speed of writing to SD card). I could recover the FS on the ssd drive. Of course, I do not have the "true" speed of ssd but I see :
-34 MB/s reading large file
-17 MB/s writing
which is 2x slower than what I get on my old server with a soft RAID on hard drives.
BUT I get nearly the same write speed if I copy an entire directory, which is then 10x faster than my HD on the server.
As my sheeva is a pbx essentially, it is far more reactive now. I'll see in one or 2 year and try not to forget to inform you.... But I think this is the way to go to avoid spending time recovering my system... and to have my customer happy!
The SSD drive is totally cold - which means it uses far less power than the sheeva it self.

best regards,
-- 
Laurent Lesage
DrEagle a écrit :
Another intersting behaviour of the SD, USB and SSD also is the write
deadlocks :
see few attempts to get explain at my fastbench page [1].

Regards,

[1] https://doukki.net/doku.php?id=wiki:tutoriels:fastbench

Le 24/08/2012 14:42, Laurent Lesage a écrit :
  
Thank you all for your opinion and experiences.

I confirm that I got nearly all the problems described by some of you :
-some SD card work, some don't.
-when they work, they have  slower access than USB sticks.
-when they works, it happens that they suddenly become "read-only". The
system continue to work but with lots of delays (of course, when the
"disk" is RO, processes accessing the disk are "waiting" and the CPU
uses more than 90% "waiting") - I don't know how it can continue worling
but it does!
-The sd card I could'nt restart finally works (I used another PC to
write on it - it seems that the SD slot of my netbook is not that
good.... I used an usb multifunction docking station for SATA/SD/MS, TF
cards, and it seems to get better results when wirintg to SD cards).
-I got a (not cheap) USB stick burned with the sheeva plug after a power
outage. I got another one (a cheap one, not surprising) burned and
terribly hot after a few days.

I also read that there was a patch for the kernel to use the SD cards,
but, as said, using the new DENX uboot, didn't make the things better -
and this seems to mean that this "driver" is not good enough to rely on.

As my sheeva is used as pbx, I must be able to rely on it. So I've
bought a SATA SSD 32Go NAND flash disk and a box to connect it to USB.
It is 2x the price but for 30 euros more, I should gain a few hours of
time and have a really reliable system. I have systems running in Africa
and it would be difficult for me to get the usb console from there... I
will test the solution and I think I will change the usb keys on all the
sheeva's running...

I'll keep the list informed ...

thanks again

-- 
Laurent Lesage



DrEagle a écrit :
    
Le 23/08/2012 21:00, mick a écrit :
  
      
On Wed, 22 Aug 2012 16:10:14 -0700
Rick Thomas <rbthomas@pobox.com> allegedly wrote:

    
        
There have been persistent reports of flaky results with SD cards on
Sheeva (and other) Plug devices.  The best theory I've heard so far
is that the SD interface hardware/software in the Plugs is vey picky
about the specs and timing of the SD card interface.  Many people
have no problems for years, but if you happen to pick a card from a
slightly out-of-spec batch, you will have no end of intermittent
problems.

Why not just go back to using a USB flash stick?

Rick

      
          
I had persistent problems with SD cards when I first bought a
sheevaplug back in 2010. (See http://baldric.net/2010/03/30/unplugged/
for example). My problems only disappeared when I moved to using a
(powered) USB disk as boot and filesystem. 

Mick
    
        
The master problem about SDHC/MMC is that the driver is a quick
adaptation of the Marvell U-Boot for denx u-boot.
It's not ported, nor maintained and not very tested by Marvell and
community.

I wrote it a few time ago to get the basic SDHC/MMC support into denx
u-boot, but the code is still buggy.

In my opinion, the mvsdio driver from Linux kernel might be ported to
denx to be mainline. I do not get it working for now...

The code for sdio driver from marvell u-boot was buggy and was just
ported without debugging.

It might work, might not.

The best method is to use NAND, USB stick are not fast enough and may be
broken also (I have a USB key drop unwritable after using it with a
sheevaplugs).
May be it is bug free now, with the latest git denx u-boot.

The IDE (SATA) for kirkwood from the git denx u-boot is now bugless and
fast enough to use in production with eSATA Sheevaplug and Kirkwood NAS
base.
---
DrEagle
  
      


  

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