[Wd_general] Compact Flash damaged after power failure

[Stéphane Mouton]

I also got successful results using CF with a system onboard trucks 
(Linux WD) and subject to brutal loss of power (ex: mandatory for fuel 
delivery).
The key factors to get a power fault tolerant system were :
1) The quality of the CF (as already mentioned in this thread) : we 
tested "supermarket" CF and experiencied size (once formatted) and 
performance differences between CF (even persistent problem on one 
sector of a CF causing problem in the dd command) . Professional grade 
CF (including in photograph shops) worked without encountering any problem.
2) The size of the CF : the smaller it is the quicker it reboots and 
restore (no problem on a 64Mb CF, experinced 1 problem on & 512Mb). Also 
try to use several partitions and set as much as you can as "read only".

Though I tried with ext3, the definitive version used ext2 and it worked 
fine. But according to what I read in this mailing list, I believe that 
use of ext3 will just improve the strength of your system.

At last, there is a bit of statistics in this problem, not just linux 
config. So don't hesitate to tell the list the result of your 
experiments, especially if you can test on a big set of CF.

Best regards

Johnson, Don a écrit :
> I have had very good luck using CF and ext3 in WD based router/nat
> boxes. Power failures are not a problem. CF incorporates wear balancing
> and distributes writes across the entire memory. If you need to write at
> times be sure to use the highest quality CF rather that the el cheapos.
>
> -----Original Message-----
> From: wd_general-bounces at lists.emji.net
> [mailto:wd_general-bounces at lists.emji.net] On Behalf Of Mark Phillips
> Sent: Monday, April 03, 2006 1:34 PM
> To: wd_general at lists.emji.net
> Subject: Re: [Wd_general] Compact Flash damaged after power failure
>
>
> Of course, the best option is to not write to the flash at all, and from
>
> your brief description, I see no reason to.  Make sure you disable 
> syslogging, and have no swap file; in fact, if your flash device has a 
> write-protect, you can turn that on and see what craps out, and then 
> remove whatever that is.  (Others here may be able to give better advice
>
> - I'm not that much of an expert)...
>
> gary.james at criticallink.com wrote:
>
>   
>>> Sean,
>>> I used to have similar problems with file system errors using ext2 if
>>>       
> the system was shutdown 
>   
>>> improperly. I would suggest moving to a journaled file system like
>>>       
> ext3 or reiser.
>   
>>> chris
>>>       
>> I am far from an expert, but I thought ext3 was not recommended for
>>     
> falsh based devices 
>   
>> because it causes excessive writes to the drive, thus hurting the life
>>     
> span of the drive.
>   
>> Gary James
>>
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>>
>>     
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-- 
Stephane Mouton
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