The other advantage is the original link adapter supports RAID-0 stripping across 4 cards which allows for faster read and write times across the 4 cards then a single card.
This is absolutely true, but I would be careful with this one.
RAID splits a single file operation across multiple drives (cards) to leverage more horsepower for faster read and writes. This is called "striping" and is what H2O is correctly describing.
Something not everyone may be aware about "RAID" is the redundancy issue. Even though it is part of the acronym, don't assume you are getting it.
The RAID 0 standard this card offers in fact by definition only gives you striping, no redundancy.
So for our purposes?
First of all, we are not supporting all this concurrent activity that needs striping speed. If you have a card that is more than adequate to handle the single task at hand - write speeds capable of maintaining an error free continuous sampling rate - a "faster" write does not add anything useful. It's not like a SQL Server that can be striped and load balances across servers. More and more users are not logging into your SD to try to make a plane reservation. Basically "more than good enough" and "better than the old more than good enough" have no practical difference.
The bigger question would be how does this widget respond to an error? I am familiar with RAID concepts but I write software not firmware or design hardware. I know just barely enough to know that you have now introduced say 4 cards into a single system that in the event any single one fails, the entire operation just failed. So you have 4 possible cards that can now fail instead of one.
There is in no uncertain terms no redundancy in the RAID 0 standard.
But how does the gizmo itself really work? In order to even work at all, the card has to "look OK" to the 722, i.e it looks like a single card even though it is in fact 4. If one errors, the SD I assume tries to close the file and start a new one like it would with a regular CF card. What does the gizmo do with that? Maybe the same as a regular CF card that was not totally fucked - it maybe loses some data and keeps going.
Maybe in fact it is even more robust to failure of any given card. But maybe it says "Sorry bud, I have 3 known good cards outta 4, but I have to say good bye anyway". This thing is not expensive and was designed I would guess for the photo market. Those guys are not capturing 2 gigs that have to be continuous.
What happens when a card error happens to a file striped across 4 cards instead of 1? Are you more likely to lose the whole thing with one or the other, or is it no different?
If they make these things with a RAID config that also offers RAID redundancy on micro cards, and it is proven technology, I'd downshift to a 702 and be all over that. RAID -0, I think I will hold off.
Many questions. Maybe someone has the answers?
Topic: 722 compact flash adapters (Read 3663 times)