So first you asked…
[quote=“yoyoma, post:1, topic:1102”]
with different HD cache sizes, what is the measurable difference in read/ write times in the Drobo?
I am geeky and want to know what the difference is.[/quote]
Then Jennifer answered…
[quote=“Jennifer, post:4, topic:1102”]
There was no measurable difference between the two speeds of drives when tested.[/quote]
At least we share the same feeling on something.
[quote=“yoyoma, post:11, topic:1102”]
I have asked them to measure something that is not measurable?[/quote]
Based on Jennifer’s answer, they measured, and there is no difference.
If the difference is not measurable, the difference is, for all intents and purposes, zero. It’s like asking someone to measure the difference in length between two pieces of wood. They pull out a tape measure and get 360mm on one piece, and 360mm on the other piece. There is no measurable difference.
You are asking for what the difference is, and the difference is zero. Not close to zero, not almost zero, but zero. So your question should be answered but you have a new question, “What is the read/write speed of Drobo?”
Well, that one is tricky.
ajspencer has already explained that the drives themselves are not the limiting factor in Drobo read/write speed (save for possible DroboElite), so cache size doesn’t matter.
Effective (from the client side) Drobo read/write speed varies depending on the conditions - whether there is simultaneous access, what interface is being used, whether the data request is large or small, how full the drive is. However, given all other variables are the same, the cache size of the drive does not affect the speed.
So far, to recap, the questions and answers on this thread so far are:
Is there a difference in read/write speed between different drive cache sizes?
Answer: No. (Jennifer says “no measureable difference”)
Does drive cache size affect Drobo performance?
Answer: No. (ajspencer says drive cache is not the limiting factor)
[*]Did DRI test performance of drives with different cache sizes?
Answer: Yes, otherwise they could not state that there is no measurable difference. (A difference of no difference still requires measurement)
If, in Drobo world, f_8MBcache(a) = f_16MBcache(a)
Then for any a (being the same make/model drive), the result of f_8MBcache and f_16MBcache are equal.
Hahaha, Docchris types faster than I do. Or maybe he’s just more concise.