Re: MXI Security Stealth MXP - data corruption

On Sun, Sep 02, 2007 at 10:14:58PM -0400, Alan Stern wrote:
> > Please Cc me on any replies, since I'm not subscribe to this list.  
> > Thanks.

> It's quite possible there's a bug in the device, one that is somehow 
> triggered by Linux but not by Windows or Mac OS X.  However I have no 
> idea what such a bug might be or how to avoid it.

Well, my colleague found a solution:

"The problem is that the Stealth MXP device can't handle transfers 
greater than 64 Kb at a time. By default, linux attempts to transfer 
120Kb at a time resulting in corruption. The Windows default is 64Kb, 
so no corruption. My guess is that OS X is using 64Kb transfers as 
well.

I changed the max_sectors value for my device (sdb at the moment) from 
240 (240 sectors x 512 bytes per sector = 120Kb per transfer) to 128 
(128 sectors x 512 bytes per sector = 64Kb per transfer) and was able 
to transfer a 3.2Gb file without error, unmount, remount, and verify 
there were no errors. When I set the max_sectors value to 136 
(max_sectors must be in multiples of 8) reading the data showed 
errors. Setting it back to 128 and remounting allowed reading the data 
without errors.

With the max_sectors value set to 128 fsck comes up clean.

So there is the problem, but I don't know if this is a constraint of 
the chipset in the drive or a firmware fixable type thing. We will 
have to see what technical support at MXI has to say.

The fix is simple. As root (change the device as needed)...

  echo 128 >/sys/block/sdb/device/max_sectors

Changes to this value don't go into effect until the device is 
unmounted and remounted.

Here is the page I found the solution on:

http://www.linux-usb.org/FAQ.html#i5
"

-------------------------------------------------------------------------
This SF.net email is sponsored by: Splunk Inc.
Still grepping through log files to find problems?  Stop.
Now Search log events and configuration files using AJAX and a browser.
Download your FREE copy of Splunk now >>  http://get.splunk.com/
_______________________________________________
[email protected]
To unsubscribe, use the last form field at:
https://lists.sourceforge.net/lists/listinfo/linux-usb-users