Hello,
Subject: SD Card Write Limit with VFSFileWrite
From: autocode1 <[EMAIL PROTECTED]>
Date: Thu, 12 Feb 2004 19:28:31 -0800 (PST)
X-Message-Number: 42
>>I wrote a logging application for my Tungsten T
that logs about 300 bytes every 1/4 second to
an SD card file via VFSFileWrite. Doing the math,
the file grows about 4mb per hour.
>>This represents about 5 complete fill-the-card,
erase-the-card cycles with my Lexar 256mb sd card
before failure (using 168 hours per week). Spec
is > 100,000 write cycles.
>> My question is, what am I missing?
Maybe...depending on your code:
I just calculate the total writes, which I pasted here from my Excel
spreadsheet, based on your statement:
3,600 secs per hour
24 hours per day
86,400 seconds per day
4 writes per second
345,600 total writes per day
14 days (2 weeks)
4,838,400 total writes for 2 weeks
You're killing your SD card easily based on that calculations.
Every write process "burns" the data to SD card, counting the write
cycle as "1".
Solution: Use memory to store the data, then append the new log data to
SD card every 30 seconds. SD card will last much longer, and would
thank you many times for keeping it alive for much longer.
My advice: Make sure that last write is issued to SD card if the
application is about to exit from memory.
Cheers,
Robert J. Rademacher
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