[Tig] [Tif] removable storage disks

[Joe Owens]

Quoting:
" any RAID 0 product since such products are at least 2X (but probably
> 4X) more likely to fail than single drive units.
>

I haven't heard anything like that before. Why do you think that's  
the case?"

Maybe its the cascading MTBF reliability... or UNreliability, if you  
prefer.  RAID 0 has to stay robust across the stripe, and anytime you  
"gang" devices with the same failure rate, the probability of failure  
goes up, not down.  Third year Engineering Statistics, at least 30  
years ago...  probably grade 9 math now...

The classic analysis problem is to sort out the probability of  
success for a device with a certain failure rate, then recalculate   
the mission success with a backup system in place.  Factors then  
involve:  the reliability of error-sensing, success of engaging the  
backup system, the failure rate of the backup system itself, ...  
etc.   My recollection is that NASA had to hit something like 10-9's  
to approve a device for inclusion on a SaturnV rocket.  Thats one  
chance in 10 to the 10th power that it would fail...   remember there  
were millions of things could go wrong.

Me, I just take a lot of ginger care of external drives, and  
religiously observe procedures for powering up and down and  
ejection.  I'm sure I'll lose something eventually, though...  
probability being what it is, and my hitchhikers' guide attitude  
towards what is inevitable, although that does not apply to the  
federal lottery.

Joe Owens
Presto!Digital Colourgrade
302-9664 106 Avenue
Edmonton, Alberta T5H0N4
+1 780 421-9980
jpo at prestodigital.ca