Re: RAID 5 doesn't scale

[Peter Landmann <sfrazt@googlemail.com>]

> If you're running the tests for multiple minutes and many tens of GBs at
> a time, then this slowdown is due to garbage collection, not stripe
> cache sizing.

You are right. I wrote about that in another post.
> 
> You are not performing proper testing methodologies, and you're jumping
> to conclusions way too quickly, and likely incorrectly.

See above.
> 
> If you're not familiar with SSD garbage collection then you must learn
> about it.  It will affect everything you do with SSDs, especially when
> doing these kinds of tests where you're writing huge amounts of data to
> the flash cells.  Wear leveling, part of garbage collection,
> dramatically slows down SSD throughput.  And when you're pushing this
> much data, TRIM won't help.  It'll actually slow the SDDs down even more.

In a shortage of time i was to fast .. I'm sorry for the trouble but at least 
some people and i could learn something about md :)

Peter