At 09:12 PM 10/26/98 -0500, Cary B. O'Brien wrote:
>>
>> We are building an embedded Linux system and the spec calls for ten year
>> lifespan. These systems will be located at radio sites with various
>> environments. We are considering using Sandisk Flashdrives but I was
>> wondering if there are any industrial strength, long life laptop size
>> IDE drives on the market.
>>
>We did the math on flash disks and were not happy with the
>lifetime.
>
>The MTBF for hard drives is pretty long. Picking a random
>seagate drive,
>
> http://www.seagate.com/support/disc/specs/st1133a.shtml
>
>they say the MTBF is 150,000 hours. This is 6250 days or 17
>years. So you should be ok. But anecdotal evidence says that
>drives that run for a LONG time have their lubricant crystalize
>(or soemthing like that), so they won't restart. So a PM full
>power cycle every 6 months or so might not be a bad idea.
>
>Comments?
MTBF - Mean Time BETWEEN Failures. That is the mean time from a failure,
then a repair and then the next failure. A better measure is MTTFF (Mean
Time To First Failure) There's a good explanation of this at:
http://www.quantum.com/src/whitepapers/mtbf/qntmtbf4.htm
AFR (Annualized Failure Rate) is another popular measure. 1-2% is a good
estimate, that is if you put 100 drives in the field, expect 1 or 2 to fail
each year.
Al Youngwerth
[EMAIL PROTECTED]
